ORCID Profile
0000-0003-2076-1133
Current Organisation
Nanyang Technological University
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Publisher: Elsevier BV
Date: 04-2012
Publisher: IOP Publishing
Date: 15-05-2002
DOI: 10.1143/JJAP.41.3047
Publisher: Wiley
Date: 13-01-2017
DOI: 10.1002/JRS.5081
Publisher: AIP Publishing
Date: 2009
DOI: 10.1063/1.3056180
Abstract: The effect of substrate temperature (TS) on the behavior of field emission, microstructure, optical band gap, and the surface energy of N-doped SrTiO3 thin films coated on silicon tip arrays has been examined in detail. Results indicate that the TS dominates the chemical states of nitrogen added to the sputtered SrTiO3 films and hence the observations. At the critical temperature of 600 °C, nitrogen atoms incorporate into the oxide film with sp-hybridization features. The generation of the nonbonding lone pair states narrows the optical band gap and the lone pair induced antibonding dipoles lower the threshold field for electron emission substantially. At lowered TS, molecular adsorption of nitrogen dominates. Contact angle measurements further evidence for the presence of antibonding dipole states at the surfaces which is responsible for the adsorbate-induced surface stress.
Publisher: Elsevier BV
Date: 02-2014
Publisher: AIP Publishing
Date: 05-2017
DOI: 10.1063/1.4978041
Publisher: World Scientific Pub Co Pte Lt
Date: 08-2006
DOI: 10.1142/S0219581X0600453X
Abstract: A method of impedance frequency response analysis (FRA) with template multilayer organic capacitor was studied to evaluate printable materials for all-printed organic field-effect transistors (OFETs). The new method allows us not only to characterize simultaneously dielectric and conductive behaviors of the materials but also to distinguish contributions to electrical conduction or to polarization from different sources such as dielectric layer, semiconductor layer, and different interfaces for OFETs. As a dielectric layer for OFETs, Urathan is preferred because of lower conductivity, nonmetallic conduction behavior at high temperature, and lower interfacial resistance. Conductivity and dielectric enhancement of Urathan can be realized by heating. The critical temperature for conductivity and dielectricity transition was calculated from FRA from temperature dependent experiments. The method could be a standard for fast screening and assessing printable materials for OFETs.
Publisher: American Chemical Society (ACS)
Date: 23-07-2013
DOI: 10.1021/JZ401029Z
Abstract: Goldschmidt-Pauling contraction of the H-O polar-covalent bond elongates and polarizes the other noncovalent part of the hydrogen bond (O:H-O), that is, the O:H van der Waals bond, significantly, through the Coulomb repulsion between the electron pairs of adjacent oxygen (O-O). This process enlarges and stiffens those H2O molecules having fewer than four neighbors such as molecular clusters, hydration shells, and the surface skins of water and ice. The shortening of the H-O bond raises the local density of bonding electrons, which in turn polarizes the lone pairs of electrons on oxygen. The stiffening of the shortened H-O bond increases the magnitude of the O1s binding energy shift, causes the blue shift of the H-O phonon frequencies, and elevates the melting point of molecular clusters and ultrathin films of water, which gives rise to their elastic, hydrophobic, highly-polarized, ice-like, and low-density behavior at room temperature.
Publisher: Elsevier BV
Date: 09-2006
Publisher: Springer Science and Business Media LLC
Date: 13-10-2016
DOI: 10.1038/SREP35304
Abstract: To make full use of the solar energy, exploring broad spectrum active photocatalysts has become one of the core issues for photocatalysis. Here we report a novel hexagonal 2H-MoSe 2 photocatalyst with ultraviolet (UV)-visible-near infrared (NIR) light response for the first time. The results indicate that the MoSe 2 displays excellent photo-absorption and photocatalytic activity in the reduction of Cr(VI) under UV and visible even NIR light irradiation. MoSe 2 synthesized at pH value of 2 achieves the highest Cr(VI) reduction rates of 99%, 91% and 100% under UV, visible and NIR light irradiation, respectively, which should be attributed to its comparatively higher light absorption, efficient charge separation and transfer as well as relatively large number of surface active sites. The excellent broad spectrum active photocatalytic activity makes the MoSe 2 to be a promising photocatalyst for the effective utilization of solar energy.
Publisher: World Scientific Pub Co Pte Lt
Date: 04-2009
DOI: 10.1142/S0218625X09012573
Abstract: Cu , Al , and Ti films of ~ 10 nm thickness were deposited on porous silicon (PS) at room temperature using Filtered Cathodic Vacuum Arc system and annealed at 800°C for 10 min in vacuum. The PS layers were obtained by anodization of Si wafer. X-ray photoelectron spectroscopy, photoluminescence (PL), photo-absorption (PA), and X-ray diffraction studies revealed that before annealing just Cu -deposited s le exhibited PL blueshift, PA redshift, and Si -2p level shift due to the Cu diffusion at the surface of PS. While after annealing, Cu - and Ti -deposited s les exhibited obvious PA redshift and Si -2p level shift, which arise from the crystal field variation due to the formation of Cu / Ti silicides at the surface as well as the conduction electronic transportation.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5RA26919A
Abstract: Monatomic alloying of atomic clusters emerges as a promising means for efficient catalyst development with a yet unclear mechanism.
Publisher: Elsevier BV
Date: 07-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CP55484H
Abstract: Terahertz (THz) spectroscopy has become an effective tool to characterize the low-frequency rotational and vibrational modes of molecules. In addition, novel THz dielectric responses and optical properties on the basis of molecular rotation and vibration have attracted lots of attention because of their potential application in THz devices. In this paper, the dielectric response of low-symmetric sodium nitrate crystals in the frequency range of 0.2-1.5 THz was experimentally demonstrated. Four absorption bands at 0.23, 0.47, 0.92, and 1.15 THz were observed in the dielectric spectra and were tentatively ascribed to the rotational motion of nitrate ions. Based on the molecular rotation mechanism, the dielectric anisotropy and dielectric resonance of the crystal were discussed in detail.
Publisher: Elsevier BV
Date: 06-2013
Publisher: American Chemical Society (ACS)
Date: 29-09-2004
DOI: 10.1021/JP047902X
Publisher: IOP Publishing
Date: 10-11-2000
Publisher: Springer Singapore
Date: 2019
Publisher: Elsevier BV
Date: 03-2019
Publisher: Springer Science and Business Media LLC
Date: 2000
Publisher: IOP Publishing
Date: 14-08-2004
Publisher: American Chemical Society (ACS)
Date: 23-09-2016
DOI: 10.1021/ACS.NANOLETT.6B02701
Abstract: Density functional theory (DFT) and Berry curvature calculations show that quantum anomalous Hall effect (QAHE) can be realized in two-dimensional(2D) antiferromagnetic (AFM) NiRuCl
Publisher: Elsevier BV
Date: 12-2007
Publisher: AIP Publishing
Date: 31-03-2004
DOI: 10.1063/1.1686905
Abstract: Deep level transient spectroscopy and optical absorption spectroscopy measurement revealed three outstanding features of density-of-states (DOS) appeared above the valence band edge (Ev) of Al oxide thin films. The broad peak located at 0.39 eV above Ev disappears while the other two located at 1.0 and 1.3 eV shift in position and attenuate in intensity upon annealing at 200 °C. The latter two peaks are removed by annealing at temperature up to 400 °C. The observed midgap DOS feature dynamics is in accordance with the oxygen lone pair features as confirmed earlier with Raman spectroscopy in the low-frequency ranges [C. Q. Sun et al., J. Appl. Phys. 90, 2615 (2001)] and thermal desorption measurements of other oxide surfaces.
Publisher: American Chemical Society (ACS)
Date: 24-08-2009
DOI: 10.1021/JP905336J
Publisher: IOP Publishing
Date: 05-12-2001
Publisher: Wiley
Date: 11-05-2021
Abstract: Present one‐step N 2 fixation is impeded by tough activation of the N≡N bond and low selectivity to NH 3 . Here we report fixation of N 2 ‐to‐NH 3 can be decoupled to a two‐step process with one problem effectively solved in each step, including: 1) facile activation of N 2 to NO x − by a non‐thermal plasma technique, and 2) highly selective conversion of NO x − to NH 3 by electrocatalytic reduction. Importantly, this process uses air and water as low‐cost raw materials for scalable ammonia production under ambient conditions. For NO x − reduction to NH 3 , we present a surface boron‐rich core–shell nickel boride electrocatalyst. The surface boron‐rich feature is the key to boosting activity, selectivity, and stability via enhanced NO x − adsorption, and suppression of hydrogen evolution and surface Ni oxidation. A significant ammonia production of 198.3 μmol cm −2 h −1 was achieved, together with nearly 100 % Faradaic efficiency.
Publisher: Elsevier BV
Date: 04-2019
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.BIOELECHEM.2006.01.001
Abstract: The direct electron transfer of glucose oxidase (GOD) was achieved based on the immobilization of GOD/colloidal gold nanoparticles on a glassy carbon electrode by a Nafion film. The immobilized GOD displayed a pair of well-defined and nearly reversible redox peaks with a formal potential (Eo ') of -0.434 V in 0.1 M pH 7.0 phosphate buffer solution and the response showed a surface-controlled electrode process. The dependence of Eo ' on solution pH indicated that the direct electron transfer reaction of GOD was a two-electron-transfer coupled with a two-proton-transfer reaction process. The experimental results also demonstrated that the immobilized GOD retained its electrocatalytic activity for the oxidation of glucose. So the resulting modified electrode can be used as a biosensor for detecting glucose.
Publisher: Elsevier BV
Date: 02-2023
Publisher: American Chemical Society (ACS)
Date: 25-06-2015
DOI: 10.1021/CR500651M
Publisher: Elsevier BV
Date: 06-2004
Publisher: American Physical Society (APS)
Date: 04-10-2005
Publisher: IMR Press
Date: 2005
DOI: 10.2741/1519
Abstract: Microelectrodes were fabricated to study impedance labelless detection of DNA hybridization. The probe molecule was attached onto the platinum microelectrode surface by electrochemically copolymerizing pyrrole and the probe oligonucleotides. Measured impedance complexes showed that an electrochemical redox-reaction occurred and the electron-transfer resistance increased after DNA hybridization. It was proposed that the hybridization of DNA in the conductive polymer matrix slowed down the anionic doping/undoping process, resulting impedance changes for the target DNA detection. Impedance measurements were conducted at the complementarily hybridized probe oilgomer-attached polypyrrole film electrodes in different anionic solutions to exam the anionic effects. Results showed that higher concentration and smaller size of anions had the lower electron-transfer resistance. The results not only provide further evidence to support the detection mechanism proposed, but also offer a method to improve the signal to noise ratio for the DNA biosensor. The research also tested the specificity of the methods and experimental results, indicating good specificity of the method. A concept array chip was fabricated and used to demonstrate the capability of the labelless detection method. Nano-Molar concentrations were detected and showed fairly linear responses versus the target molecule concentrations. The method is simple and inexpensive. The technique based genosensors could have potential applications in clinical diagnosis, drug discovery, environmental and food analysis.
Publisher: American Chemical Society (ACS)
Date: 27-10-2015
Publisher: Elsevier BV
Date: 2013
Publisher: IEEE
Date: 2008
Publisher: Elsevier BV
Date: 07-1999
Publisher: American Scientific Publishers
Date: 09-2013
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 2010
Publisher: Wiley
Date: 04-2006
Publisher: AIP Publishing
Date: 10-2014
DOI: 10.1063/1.4898143
Abstract: The effects of vertical compressive stress on Sb2Te3 nano-films have been investigated by the first principles calculation, including stability, electronic structure, crystal structure, and bond order. It is found that the band gap of nano-film is sensitive to the stress in Sb2Te3 nano-film and the critical thickness increases under compressive stress. The band gap and band order of Sb2Te3 film has been affected collectively by the surface and internal crystal structures, the contraction ratio between surface bond length of nano-film and the corresponding bond length of bulk decides the band order of Sb2Te3 film.
Publisher: American Physical Society (APS)
Date: 23-04-2001
Publisher: Elsevier BV
Date: 2004
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.JCIS.2013.07.045
Abstract: Bi2O3-reduced graphene oxide (RGO) composites were successfully synthesized via microwave-assisted reduction of graphite oxide in Bi2O3 precursor solution using a microwave system. Their morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) and methyl orange (MO) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, UV-vis absorption spectroscopy, and electrochemical impedance spectroscopy, respectively. The results show that the RGO addition can enhance the photocatalytic performance of Bi2O3-RGO composites. Bi2O3-RGO composite with 2 wt.% RGO achieves maximum MO and MB degradation rates of 93% and 96% at 240min under visible light irradiation, respectively, much higher than those for the pure Bi2O3 (78% and 76%). The enhanced photocatalytic performance is ascribed to the increased light adsorption and the reduction in electron-hole pair recombination in Bi2O3 with the introduction of RGO.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6CP08011A
Abstract: DFT and BOLS approximations were carried out to study the electronic and optical properties of different sizes of black phosphorus nanoribbons (PNRs) with either zigzag- or armchair-terminated edges.
Publisher: IOP Publishing
Date: 05-06-2009
Publisher: SPIE
Date: 24-10-2000
DOI: 10.1117/12.405426
Publisher: Elsevier BV
Date: 2004
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.503-504.760
Abstract: In this paper, aiming at three material parameter functions of functionally graded coating (FGC) which have different continuities, the influence of functionally gradient coating material continuity on the fracture behaviors of the crack on the interface between the base material and coating is studied. The results show that when the functionally graded coating structure is under a tension load, if the ratio of maximum elastic modulus of the FGC to the elastic modulus of the base is less than 10, the functionally graded layer which has C02 continuity can help to improve the fracture resistance of the interface crack, and if the ratio increases continuously, the functionally graded layer which has C13 continuity can help to improve the fracture resistance of the interface crack, which is of great guiding significance for practical engineering design.
Publisher: American Physical Society (APS)
Date: 03-02-2006
Publisher: American Physical Society (APS)
Date: 02-03-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0NR00245C
Abstract: Although they exist ubiquitously in human bodies and our surroundings, the impact of nonbonding lone electrons and lone electron pairs has long been underestimated. Recent progress demonstrates that: (i) in addition to the shorter and stronger bonds between under-coordinated atoms that initiate the size trends of the otherwise constant bulk properties when a substance turns into the nanoscale, the presence of lone electrons near to broken bonds generates fascinating phenomena that bulk materials do not demonstrate (ii) the lone electron pairs and the lone pair-induced dipoles associated with C, N, O, and F tetrahedral coordination bonding form functional groups in biological, organic, and inorganic specimens. By taking ex les of surface vacancy, atomic chain end and terrace edge states, catalytic enhancement, conducting-insulating transitions of metal clusters, defect magnetism, Coulomb repulsion at nanoscale contacts, Cu(3)C(2)H(2) and Cu(3)O(2) surface dipole formation, lone pair neutralized interface stress, etc, this article will focus on the development and applications of theory regarding the energetics and dynamics of nonbonding electrons, aiming to raise the awareness of their revolutionary impact to the society. Discussion will also extend to the prospective impacts of nonbonding electrons on mysteries such as catalytic enhancement and catalysts design, the density anomalies of ice and negative thermal expansion, high critical temperature superconductivity induced by B, C, N, O, and F, the molecular structures and functionalities of CF(4) in anti-coagulation of synthetic blood, NO signaling, and enzyme telomeres, etc. Meanwhile, an emphasis is placed on the necessity and effectiveness of understanding the properties of substances from the perspective of bond and nonbond formation, dissociation, relaxation and vibration, and the associated energetics and dynamics of charge repopulation, polarization, densification, and localization. Finding and grasping the factors controlling the nonbonding states and making them of use in functional materials design and identifying their limitations will form, in the near future, a subject area of "nonbonding electronics and energetics", which could be even more challenging, fascinating, promising, and rewarding than dealing with core or valence electrons alone.
Publisher: AIP Publishing
Date: 15-03-2011
DOI: 10.1063/1.3554833
Abstract: The bandgap and optical properties (dielectric functions and optical constants) of dome-shaped Ge nanocrystals (nc-Ge) with average sizes of ∼6 nm in height and ∼13 nm in diameter have been investigated using spectroscopic ellipsometry based on the Forouhi-Bloomer optical dispersion model. As compared to bulk crystalline Ge, the nc-Ge exhibited a bandgap expansion of ∼0.2 eV and a significant reduction in the dielectric function. The bandgap expansion and dielectric suppression are discussed in terms of the quantum confinement effect as well as the bond contraction model.
Publisher: World Scientific Pub Co Pte Lt
Date: 20-01-2002
DOI: 10.1142/S0217979202009470
Abstract: It has been elegantly accepted that oxygen adsorption onto the Cu (110) surface induces an expansion of the first layer-spacing and a contraction of the second in addition to the alternative Cu [001] row that is either missing or forming the O-Cu-O row of high protrusions. However, it needs yet to clarify the vertical position of the oxygen and the hard-sphere models of added-, missing- and buckled-row. Here we justify that all the structures determined and all the models developed so far are correct in the sense of numerical solutions and phenomenological descriptions. A tetrahedral bond configuration of sp-orbital hybridization developed recently, however, may serve as a criterion to identify the physical solution that could account consistently for the observations using scanning tunneling microscopy/spectroscopy (STM/S), X-ray diffraction (XRD), and ultraviolet photoelectron spectroscopy (UPS).
Publisher: IOP Publishing
Date: 05-12-2001
Publisher: American Chemical Society (ACS)
Date: 16-12-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CP04891F
Abstract: Edge-resolved strong magnetism in arsenene nanoribbon is attributed to electron entrapment induced by edge bond contraction and potential deepening.
Publisher: World Scientific Pub Co Pte Lt
Date: 10-04-1998
DOI: 10.1142/S0217979298000533
Abstract: From the perspective of bond forming, origin of phase-formation on the O-Cu(001) and the O-Cu(110)is analyzed. It is suggested that the formation of the O -1 and the hybridized- O -2 gives in nature the c (2 × 2)-O and subsequently, the [Formula: see text]phase, on the Cu(001). The re-ordering of the primary Cu 2 O units transforms the Cu(110)-(2×1)-O into the c (6 × 2)-O. As consequences of the O -2 -hybridization, the Cu(001)-[Formula: see text] differs from the Cu(110)-(2×1)-O in origin by nothing more than that the -O-Cu-chain rotates 45° to fit itself to the coordination-surrounding. It proposed that one metal atom may donate more than one-electron to different oxygen atoms. However, one oxygen, with two directional bonding orbitals and two nonbonding orbitals, can never get more than one-electron from a specific metal atom. The sp-hybridization of oxygen cannot occur before its two bonding orbitals are fully occupied. Besides the ionization of oxygen and metal atoms, the polarization of the metal and the hybridization of O -2 dominate the processes of oxidation and the behavior of the oxides. Further considerations are required regarding how the O-coverage reversibly varies the valence-state of oxygen, and how the coverage and temperature reassemble the Cu 2 O on the Cu(110).
Publisher: Elsevier BV
Date: 10-2003
Publisher: Springer Science and Business Media LLC
Date: 05-01-2007
DOI: 10.1007/S00216-006-1013-1
Abstract: In this work we present a strategy for the covalent immobilization of periodate oxidized glucose oxidase (IO(4)(-) - GOx) to aminated silica nanoparticles (ASNPs) modified on gold electrodes. Silica nanoparticles greatly enhanced the catalytic ability of GOx toward the oxidation of glucose and improved the electron transfer between the GOx and the electrode surface. ASNPs of varying size--that is 100, 80, 60, and 30 nm--were prepared, and they were used to fabricate biosensors. Electrochemical impedance spectroscopy (EIS) of ferrocyanide followed the assembly process and verified the successful immobilization of IO(4)(-) - GOx on ASNPs modified on gold electrodes. From the analysis of catalytic signals of biosensors using different sizes of ASNPs under the same conditions, the surface concentration of electrically wired enzyme (Gamma (ET)) was estimated and was found to increase with decreasing ASNPs size. Therefore, the sensitivity of biosensors using smaller ASNPs was higher than that using larger particles. Specifically, we utilized the ASNPs with optimal size (30 nm) to fabricate the glucose biosensor. The resulting electrodes showed a wide linear response to glucose at least to 6 mM and reached 95% of the steady-state current in less than 4 s with a sensitivity of 5.02 microA mM(-1) cm(-2) and a detection limit of 0.01 mM. The biosensor also showed excellent stability and good reproducibility.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA13877B
Abstract: The double-layer model of oxygen adsorption is proposed for the initial oxidation of the Ti(0001) surface based on diffusion barrier analysis.
Publisher: AIP Publishing
Date: 15-04-2008
DOI: 10.1063/1.2907947
Abstract: The atomistic origin of the atomic vacancy or nanocavity induced hardening in hollow nanotubes and nanoporous structures has long been a puzzle. An analysis from the perspective of bond-order–length-strength correlation mechanism [C. Q. Sun, Prog. Solid State Chem. 35, 1 (2007)] has led to solutions that show that the shortened and strengthened bonds between the undercoordinated atoms in the negatively curved surface skins dominate the observed nanocavity strengthening and thermal instability of the porous structures. It is suggested that the broken bond derived local strain and quantum trapping and the associated energy densification provide pinning centers for inhibiting atomic dislocations and that the broken bond induced cohesive energy dropping dominate the thermal instability. On the other hand, nanocavities also provide sites that initiate the structure failure under plastic deformation. The agreement between predictions and the experimentally observed size dependence of mechanical strength of some nanoporous materials and the well-known phenomenon of hollow tube strengthening evidences for the proposed mechanism.
Publisher: Elsevier BV
Date: 08-2019
Publisher: Elsevier BV
Date: 08-2019
Publisher: AIP Publishing
Date: 29-07-2003
DOI: 10.1063/1.1594821
Abstract: Dielectric impedance measurements of porous silicon within the frequency range of 50 Hz–1.0 MHz and temperature range of 298–798 K revealed three semicircles in a Cole–Cole plot when the temperature is raised to 773 K they are thought to correspond to contributions from the grain interior, grain boundary, and electrode/film interface, respectively. The enhancement in conductivity by heating follows an Arrhenius law with an activation energy transition from 0.07 to 0.79 eV at ∼565 K, which originates from band tail hopping that occurs around the Fermi edge. At a critical temperature, a high degree of dispersion in the real and imaginary parts of the permittivity also occurs at low frequencies. This dispersion behavior is interpreted as a combination of electron-lattice polarization associated to the band tail hopping and the crystal field weakening due to thermal expansion.
Publisher: AIP Publishing
Date: 29-07-2003
DOI: 10.1063/1.1594822
Abstract: Carbon nitride films have been deposited by rf reactive magnetron sputtered graphite carbon in an N2 discharge. The process parameters, viz., nitrogen partial pressure (PN2), substrate temperature (Ts), and substrate bias (Vb) were varied in order to investigate their influence on the field emission properties. The effective work function for carbon nitride films determined using the Fowler–Nordheim equation is in the range of 0.01–0.1 eV. Insight is presented into the nitrogen-lowered threshold of cold cathode electron emission of carbon from the perspective of nitride tetrahedron bond formation. The involvement of nonbonding (lone pair) and lone-pair-induced antibonding (dipole) states is suggested to be responsible for lowering the work function and hence the electron emission threshold. It is found that the substrate temperature of 200 °C, floating potential at the substrate, and nitrogen partial pressure of 0.3 Pa are favorable to promote the reaction that lowers the work function.
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 09-2004
Publisher: Wiley
Date: 12-04-2010
Publisher: Elsevier BV
Date: 02-2015
Publisher: Wiley
Date: 30-01-2007
Publisher: American Chemical Society (ACS)
Date: 22-08-2016
DOI: 10.1021/ACS.LANGMUIR.6B01660
Abstract: Water nanobubbles manifest fascinatingly higher mechanical strength, higher thermal stability, and longer lifetime than macroscopic bubbles thus, they provide an important impact in applications in the biomedical and chemical industries. However, a detailed understanding of the mechanism behind these mysteries of nanobubbles remains a challenge. Consistency between quantum computations and Raman spectrometric measurements confirmed our predictions that a nanobubble skin shares the same supersolidity with molecular clusters, skins of bulk water, and water droplets because of molecular undercoordination (fewer than four nearest molecular neighbors). Molecular undercoordination (coordination number Z
Publisher: IMR Press
Date: 2005
DOI: 10.2741/1716
Abstract: A simple and sensitive electrochemical immunosensor with impedance labelless detection and novel data processing method was investigated. One-step copolymerization was used to electrochemically deposit an antibody impregnated polypyrrole film on a glassy carbon electrode surface for the immunosensor. Impedance measurements provided a labelless or reporterless method to detect antibody (Ab)-antigen (Ag) interactions. Dimensionless analysis was employed to successfully process the measured impedance data. Since the method derived unit impedance change to eliminate or reduce the variation of the bulk electronic properties of Ab olypyrrole films, the signal to noise ratio (S/N) was significantly improved for high sensitivity and specificity. Nonspecific binding effect was studied by array electrode chips and was found out that the polypyrrole electrode without antibody attachment had much stronger nonspecific binding effect than the Ab olypyrrole electrode incubation followed by thoroughly washing significantly reduced the nonspecific interference. 10 pg/ml detection limit and superior specificity were achieved by the method, demonstrating a highly sensitive labelless immunosensor in comparison with the detection limit of ng -microgram/ml for the reported polypyrrole based immunosensors. The electrochemical immunosensors presented in this paper, due to its simplicity, low cost, high sensitivity and superior specificity, could be an invaluable tool for clinical diagnostics and could have potential applications in drug discovery, environmental and food analysis.
Publisher: American Chemical Society (ACS)
Date: 23-10-2002
DOI: 10.1021/JP0266805
Publisher: Organisation for Economic Co-Operation and Development (OECD)
Date: 2014
DOI: 10.1787/608033612455
Publisher: Elsevier BV
Date: 02-2005
Publisher: IEEE
Date: 2010
Publisher: American Chemical Society (ACS)
Date: 28-08-2008
DOI: 10.1021/JP8049558
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B917326A
Abstract: Incorporating the BOLS correlation algorithm [Y. Sun, J. Phys. Chem. C, 2009, 113, 14696] into high-resolution XPS measurements [J. N. Andersen, et al., Phys. Rev. B: Condens. Matter, 1994, 50, 17525 A. Baraldi, et al., New J. Phys., 2007, 9, 143] has produced an effective way of determining the 3d(5/2) energy levels of isolated Rh(302.163 +/- 0.003 eV) and Pd (330.261 +/- 0.004 eV eV) atoms and their respective bulk shifts (4.367 and 4.359 eV) with a refinement of the effective atomic coordination numbers of the top (100), (110), and (111) atomic layers (4.00, 3.87, and 4.26, respectively). It is further confirmed that the shorter and stronger bonds between under-coordinated atoms induce local strain and skin-depth charge-and-energy quantum trapping and, hence, dictate globally the positive core level binding energy shifts.
Publisher: Informa UK Limited
Date: 11-2000
Publisher: Wiley
Date: 11-05-2021
Abstract: Present one‐step N 2 fixation is impeded by tough activation of the N≡N bond and low selectivity to NH 3 . Here we report fixation of N 2 ‐to‐NH 3 can be decoupled to a two‐step process with one problem effectively solved in each step, including: 1) facile activation of N 2 to NO x − by a non‐thermal plasma technique, and 2) highly selective conversion of NO x − to NH 3 by electrocatalytic reduction. Importantly, this process uses air and water as low‐cost raw materials for scalable ammonia production under ambient conditions. For NO x − reduction to NH 3 , we present a surface boron‐rich core–shell nickel boride electrocatalyst. The surface boron‐rich feature is the key to boosting activity, selectivity, and stability via enhanced NO x − adsorption, and suppression of hydrogen evolution and surface Ni oxidation. A significant ammonia production of 198.3 μmol cm −2 h −1 was achieved, together with nearly 100 % Faradaic efficiency.
Publisher: Elsevier BV
Date: 02-2003
Publisher: Elsevier BV
Date: 03-1998
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CC06670E
Abstract: Palladium-catalyzed [3+2] annulation of allenic esters with azomethine imines affording biologically interesting tetrahydropyrazoloisoquinoline derivatives.
Publisher: Elsevier BV
Date: 10-2000
Publisher: World Scientific Pub Co Pte Lt
Date: 06-2008
DOI: 10.1142/S1793292008000976
Abstract: Incorporating the bond–order–length–strength correlation mechanism [C. Q. Sun, Prog. Solid State Chem.35, 1 (2007)] and Born's criterion for melting [J. Chem. Phys.7, 591 (1939)] into the conventional Hall–Petch relationship has turned out an analytical expression for the size and temperature dependence of the mechanical strength of nanograins, known as the inverse Hall–Petch relationship (IHPR). Reproduction of the measured IHPR of Ni , NiP , and TiO 2 nanocrystals revealed that: (i) the competition between the size-induced energy–density gain and atomic cohesive energy loss in the surface skins of nanograins originate from the IHPR (ii) the competition between the activation and inhibition of atomic dislocations motion activate the entire IHPR behavior (iii) the bond nature involved and the T/T m ratio between the temperature of operating and the temperature of melting dictate the measured strongest sizes of a given specimen (iv) a quasimolten phase present before melting determines the size-induced softening and the superplasticity of nanostructures.
Publisher: Elsevier BV
Date: 11-2008
Publisher: Trans Tech Publications, Ltd.
Date: 12-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.602-604.1596
Abstract: It is assumed that the physical parameters of functionally graded coating material accords with the variation of degree n polynomial, and based on this material model, the behavior of crack fracture on the interface of functionally graded coating is studied. The results show that when the functionally graded coating structure bears a tension load, stress intensity factors of mode I and mode II exist at the same time generally, and the intensity factor of mode I occupies a leading position all along. Besides, when the elastic modulus ratio of the base to the functionally graded coating top is 5 and the elastic modulus of functionally graded coating varies linearly, the stress intensity factor of interface crack is the smallest, and with the increasing of elastic modulus ratio, the optimal non-uniform parameter tends to be larger than 1.
Publisher: Elsevier BV
Date: 05-2004
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.CIS.2019.03.003
Abstract: Water dissolves salt into ions and then hydrates the ions to form an aqueous solution. Hydration of ions deforms the hydrogen bonding network and triggers the solution with what the pure water never shows such as conductivity, molecular diffusivity, thermal stability, surface stress, solubility, and viscosity, having enormous impact to many branches in biochemistry, chemistry, physics, and energy and environmental industry sectors. However, regulations for the solute-solute-solvent interactions are still open for exploration. From the perspective of the screened ionic polarization and O:H-O bond relaxation, this treatise features the recent progress and a perspective in understanding the hydration dynamics of Hofmeister ions in the typical YI, NaX, ZX
Publisher: IOP Publishing
Date: 18-04-2001
Publisher: AIP Publishing
Date: 24-04-2006
DOI: 10.1063/1.2198821
Abstract: The experimental results in size dependence of electronic structure and optical band gap show that the nanocrystalline ZnO has two binding states which energies are lower than that of the bulk ZnO. This size dependence of binding states is associated with the number of broken bonds of the in idual Zn ion, which could be modified by size reduction in nanoscale. Varying the number of broken bonds on the surface and the underneath layer might result in possible complications in the electronic structure of the nanocrystalline ZnO, thus giving rise to different optical properties rather than those relating to quantum size effects.
Publisher: Inderscience Publishers
Date: 2009
Publisher: Springer Science and Business Media LLC
Date: 21-01-2023
DOI: 10.1038/S41467-023-35913-6
Abstract: Heteroatom-doping is a practical means to boost RuO 2 for acidic oxygen evolution reaction (OER). However, a major drawback is conventional dopants have static electron redistribution. Here, we report that Re dopants in Re 0.06 Ru 0.94 O 2 undergo a dynamic electron accepting-donating that adaptively boosts activity and stability, which is different from conventional dopants with static dopant electron redistribution. We show Re dopants during OER, (1) accept electrons at the on-site potential to activate Ru site, and (2) donate electrons back at large overpotential and prevent Ru dissolution. We confirm via in situ characterizations and first-principle computation that the dynamic electron-interaction between Re and Ru facilitates the adsorbate evolution mechanism and lowers adsorption energies for oxygen intermediates to boost activity and stability of Re 0.06 Ru 0.94 O 2 . We demonstrate a high mass activity of 500 A g cata. −1 (7811 A g Re-Ru −1 ) and a high stability number of S-number = 4.0 × 10 6 n oxygen n Ru −1 to outperform most electrocatalysts. We conclude that dynamic dopants can be used to boost activity and stability of active sites and therefore guide the design of adaptive electrocatalysts for clean energy conversions.
Publisher: American Chemical Society (ACS)
Date: 04-09-2008
DOI: 10.1021/MA801345K
Publisher: American Chemical Society (ACS)
Date: 08-11-2008
DOI: 10.1021/JP807580T
Publisher: American Chemical Society (ACS)
Date: 17-09-2019
Abstract: Density functional computation revealed that in YOH solvation (Y = Li, Na, and K), the Y
Publisher: Elsevier BV
Date: 12-2003
Publisher: American Chemical Society (ACS)
Date: 10-08-2023
Publisher: Elsevier BV
Date: 06-2005
Publisher: IOP Publishing
Date: 21-08-2001
Publisher: Elsevier BV
Date: 05-2018
Publisher: American Scientific Publishers
Date: 07-2007
DOI: 10.1166/JNN.2007.434
Abstract: Energy shifts in the Si 2p levels of the five Si oxidation states Sin+ (n = 0, 1, 2, 3, 4) in the system of Si nanocrystals embedded in SiO2 matrix have been determined. The thermal annealing effect on the energy shifts has been studied. The result suggests that the Si nanocrystals and the SiO2 are thermally stable but the annealing can cause some structural deformations such as changes in the bond lengths and bond angles for the suboxides Si2O and SiO. The energy shifts generally show a linear dependence on the oxidation state n, suggesting that the energy shifts could be mainly determined by the nearest-neighbor oxygen atoms. It is shown that the chemical structures of the system are similar to those of the conventional SiO2/Si system in terms of the energy shifts.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CP00088D
Abstract: The chemistry and physics of under-coordination at a surface, which determines the process of catalytic reactions and growth nucleation, is indeed fascinating. However, extracting quantitative information regarding the coordination-resolved surface relaxation, binding energy, and the energetic behavior of electrons localized in the surface skin from photoelectron emission has long been a great challenge, although the surface-induced core level shifts of materials have been intensively investigated. Here we show that a combination of the theories of tight binding and bond order-length-strength (BOLS) correlation [C. Q. Sun, Prog. Solid State Chem., 2007, 35, 1-159], and X-ray photoelectron spectroscopy (XPS) has enabled us to derive quantitative information, by analyzing the Be 1s energy shift of Be(0001), (1010), and (1120) surfaces, for demonstration, regarding: (i) the 1s energy level of an isolated Be atom (106.416 ± 0.004 eV) and its bulk shift (4.694 eV) (ii) the layer- and orientation-resolved effective atomic coordination (3.5, 3.1, 2.98 for the first layer of the three respective orientations), local bond strain (up to 19%), charge density (133%), quantum trap depth (110%), binding energy density (230%), and atomic cohesive energy (70%) of Be surface skins up to four atomic layers in depth. It is affirmed that the shorter and stronger bonds between under-coordinated atoms perturb the Hamiltonian and hence the fascinating localization and densification of surface electrons. The developed approach can be applied to other low-dimensional systems containing a high fraction of under-coordinated atoms such as adatoms, atomic defects, terrace edges, and nanostructures to gain quantitative information and deeper insight into their properties and processes due to the effect of coordination imperfection.
Publisher: Elsevier BV
Date: 04-2016
Publisher: Elsevier BV
Date: 04-2000
Publisher: IOP Publishing
Date: 22-08-2002
Publisher: Qeios Ltd
Date: 20-06-2021
DOI: 10.32388/7TVP8O
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 05-2005
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9RA00673G
Abstract: The electronic structures of two-dimensional (2D) indium (In) and bismuth (Bi) metal on BN nanosheets are systematically studied using hybrid density functional theory (DFT).
Publisher: Elsevier BV
Date: 07-2019
Publisher: American Physical Society (APS)
Date: 09-06-2004
Publisher: World Scientific Pub Co Pte Lt
Date: 30-01-1997
DOI: 10.1142/S0217984997000128
Abstract: The modelling analysis herein and corresponding VLEED calculations suggest that the formation of the O -1 and the hybridised- O -1 effects in nature the c(2×2)-O and subsequently the [Formula: see text] phase on the O-Cu(001) surface.
Publisher: Elsevier BV
Date: 2003
Publisher: IOP Publishing
Date: 1999
Publisher: Qeios Ltd
Date: 03-07-2021
DOI: 10.32388/70MB7R
Publisher: American Scientific Publishers
Date: 03-2009
DOI: 10.1166/JNN.2009.395
Abstract: Molecular dynamics calculations of the fluctuation of bond vibration revealed the shell-resolved mode of surface melting of the a closed-shell cluster containing 147 atoms with Lennard-Jones type interaction. It is found that the surface melting is imitated by the migrating of the vertex atoms. Although the melting process of the LJ147 cluster could be ided into discrete stages of surface shell-by-shell melting in general, there is still a continuous process of melting from the surface shell to the core interior.
Publisher: IOP Publishing
Date: 29-05-2002
Publisher: Bentham Science Publishers Ltd.
Date: 05-04-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP00081A
Abstract: Consistency between density functional theory (DFT) calculations and experimental observations confirmed our predictions on the behaviour of local bonds, and the electron binding energy of cuboctahedral and Marks decahedral structures of Ag and Cu nanoclusters. The shorter and stronger bonds between under-coordinated atoms cause local densification and quantum entrapment of the core electrons, which polarize the otherwise conducting electrons (valence electrons). Such strong localization may result in extraordinary catalytic and plasmonic properties in Ag and Cu nanoclusters.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP03669G
Abstract: O:H–O bond anomalous relaxation and the skin high thermal-diffusivity cool hotter water faster than usual in the non-adiabatic ambient system.
Publisher: AIP Publishing
Date: 12-05-2003
DOI: 10.1063/1.1576890
Publisher: AIP Publishing
Date: 27-08-2001
DOI: 10.1063/1.1394721
Abstract: Crystallization of La2/3Ba1/3MnO3+δ oxide, which resulted in a twin-type lamella microstructure, was studied in the present work. Thermomechanical and high-temperature x-ray diffraction analyses revealed that the twin crystallization occurred at 548 K. The saturation magnetization of the twin-grained La2/3Ba1/3MnO3+δ oxide was shown much higher than the nontwin oxides. This is probably due to the easy alignment of the domains by the rearrangement of the dislocations in the twin-grain boundaries.
Publisher: Elsevier BV
Date: 07-2006
Publisher: Wiley
Date: 21-09-2017
Publisher: Elsevier BV
Date: 2012
Publisher: AIP Publishing
Date: 04-2011
DOI: 10.1063/1.3569743
Abstract: As a group of wonder materials, gold and silver at the nanoscale demonstrate many intriguing properties that cannot be seen from their bulk counterparts. However, consistent insight into the mechanism behind the fascinations and their interdependence given by one integrated model is highly desirable. Based on Goldschmidt-Pauling’s rule of bond contraction and its extension to the local bond energy, binding energy density, and atomic cohesive energy, we have developed such a model that is able to reconcile the observed size dependence of the lattice strain, core level shift, elastic modulus, and thermal stability of Au and Ag nanostructures from the perspective of skin-depth bond order loss. Theoretical reproduction of the measured size trends confirms that the undercoordination-induced local bond contraction, bond strength gain, and the associated binding energy density gain, the cohesive energy loss and the tunable fraction of such undercoordinated atoms dictate the observed fascinations, which should shed light on the understanding of the unusual behavior of other nanostructured materials as well.
Publisher: AIP Publishing
Date: 26-09-2011
DOI: 10.1063/1.3645015
Abstract: The thermally softened and the mechanically stiffened graphene phonons have been formulated from the perspective of bond order-length-strength correlation with confirmation of the C–C bond length in the single-layer graphene contracting from 0.154 to 0.125 nm and the binding energy increasing from 0.65 to 1.04 eV. Matching theory to the measured temperature- and pressure-dependent Raman shift has derived that the Debye temperature drops from 2230 to 540 K, the atomic cohesive energy drops from 7.37 to 3.11 eV/atom, and the binding energy density increases from 250 to 320 eV/nm3 compared with the respective quantities of bulk diamond.
Publisher: American Chemical Society (ACS)
Date: 07-01-2010
DOI: 10.1021/JP909952C
Abstract: An analytical form connecting the energy shift of Raman modes directly to the bonding identities (order, nature, length, energy) of a specimen and the response of the bonding identities to the applied stimuli of temperature and pressure was presented for a deeper understanding of the atomistic origin of the ZnO Raman shift. Theoretical reproduction based on the BOLS correlation theory [Sun, C. Q. Prog. Solid State Chem. 2007, 35, 1] and the local bond average (LBA) approach [Sun, C. Q. Prog. Mater. Sci. 2009, 54, 179] of the measurements revealed that the thermally softened ZnO Raman modes arise from bond expansion and bond weakening due to vibration and that the pressure-stiffened Raman modes result from bond compression and bond strengthening due to mechanical work hardening. The developed approach could be useful in generalizing the lattice dynamics directly to the process of vibration and relaxation of a representative bond of the specimen under external stimuli.
Publisher: AIP Publishing
Date: 11-2015
DOI: 10.1063/1.4936250
Abstract: Incorporating the bond order-length-strength (BOLS) notion with the Ising premise, we have modeled the size dependence of the Neel transition temperature (TN) of antiferromagnetic nanomaterials. Reproduction of the size trends reveals that surface atomic undercoordination induces bond contraction, and interfacial hetero-coordination induces bond nature alteration. Both surface and interface of nanomaterials modulate the TN by adjusting the atomic cohesive energy. The TN is related to the atomic cohesive/exchange energy that is lowered by the coordination number (CN) imperfection of the undercoordinated atoms near the surface and altered by the changed bond nature of epitaxial interface. A numerical match between predictions and measurements reveals that the TN of antiferromagnetic nanomaterials declines with reduced size and increases with both the strengthening of heterogeneous bond and the increase of the bond number.
Publisher: Elsevier BV
Date: 10-2009
Publisher: IOP Publishing
Date: 19-06-2014
Publisher: IOP Publishing
Date: 23-05-2008
DOI: 10.1143/JJAP.47.4226
Publisher: American Physical Society (APS)
Date: 15-01-1995
Publisher: Elsevier BV
Date: 09-2001
Publisher: World Scientific Pub Co Pte Lt
Date: 30-10-1997
DOI: 10.1142/S021798499700133X
Abstract: New insight into the nature and formation of the multiphase ordering of oxygen onto threefold sites of fcc(110) (Rh, Pd and [Formula: see text] analogue) is presented. By including bond-to-band model and the potential-barrier for oxygen-metal chemisorption with theoretical and experimental observations, it is shown that the multiphase ordering, composed of (2×1)pmg, (2×1)p2mg and (2×2)p2mg structures, originates from the hybridized- O -2 forming at different oxygen coverages with a specific bonding environment. Unlike the long-bridge sited O -2 ions on the Cu(Ni, Ag)(110) which give the missing-row type reconstruction, the threefold-coordinated O -2 ions on the Rh(Pd)(110) form a tetrahedron through one bond to the metal atom underneath and two nonbonding lone pairs acting on its two neighbors in the first layer. In the (2×1)p2mg structure, the lack of one metal atom for the tetrahedron is compensated by a virtual bond pulling the electron-cloud of the dipoles that are induced by the lone pairs of other O -2 ions. The tetrahedron in the (2×2)pg structure requires an electron from a metal atom in the next nearest row at the surface. Therefore, the bond network interlocks all the surface atoms and thereby, no atoms are missing. The zigzag protrusions in the STM images are recognized as metal dipoles deformed by the lone pairs of O -2 ions. The depressions correspond to rows of M + metal ions other than missing-row vacancies as had been expected previously.
Publisher: IOP Publishing
Date: 17-11-1999
Publisher: Elsevier BV
Date: 06-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B9NR00326F
Abstract: Relativistic density functional theory calculations have been conducted to examine the effect of atomic under-coordination on the crystal structure, binding energy, and electron configuration of cuboctahedral and Marks decahedral gold clusters. Trend consistency between calculations and experimental observations confirmed the predictions made using BOLS correlation theory, suggesting that the shorter-and-stronger bonds between under-coordinated atoms induce local structure relaxation, potential well depression, and the associated local charge and energy densification, as well as the polarization of the otherwise conducting s-electrons (valence charge) by the densely- and tightly-trapped core electrons of which the binding energy shifts positively to deeper energies. Findings are in good agreement with scanning tunneling microscopy/spectroscopy results from monomers, dimers, chain ends, and nanostructures of gold and other metals.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP01117G
Abstract: The valence band polarization of an under-coordinated corner atom enhances the electron-donation ability and enables the C–H oxidation of an Au nanoisland.
Publisher: Informa UK Limited
Date: 08-2000
Publisher: EDP Sciences
Date: 12-1988
Publisher: Trans Tech Publications, Ltd.
Date: 06-2008
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.47-50.1023
Abstract: Analytical expressions for crack-tip higher order stress functions for a plane crack in a special functionally graded material (FGM), which has an variation of elastic modulus in 1 2 power form along the gradient direction, are obtained through an asymptotic analysis. The Poisson’s ratio of the FGM is assumed to be constant in the analysis. The higher order fields in the asymptotic expansion display the influence of non-homogeneity on the structure of crack-tip fields obviously. Furthermore, it can be seen from expressions of higher order stress fields that at least three terms must be considered in the case of FGMs in order to explicitly account for non-homogeneity effects on the crack- tip stress fields. These results provide the basis for fracture analysis and engineering applications of this FGM.
Publisher: Elsevier BV
Date: 09-2005
Publisher: IOP Publishing
Date: 17-07-2001
Publisher: American Chemical Society (ACS)
Date: 19-09-2023
Publisher: American Chemical Society (ACS)
Date: 08-05-2003
DOI: 10.1021/JP0272015
Publisher: American Chemical Society (ACS)
Date: 21-06-2023
DOI: 10.1021/JACS.3C03022
Publisher: Elsevier BV
Date: 06-1997
Publisher: Elsevier BV
Date: 05-2010
Publisher: American Chemical Society (ACS)
Date: 29-12-2009
DOI: 10.1021/JP909549F
Publisher: American Chemical Society (ACS)
Date: 08-11-2011
DOI: 10.1021/JP209933V
Publisher: Elsevier BV
Date: 2000
Publisher: AIP Publishing
Date: 22-07-2002
DOI: 10.1063/1.1497712
Abstract: Smooth modulation structure of Mg–B alloy in the quenched reaction product of Mg and amorphous B was studied. It indicates that the MgB2 formed possibly in spinodal decomposition, thus resulting in MgB2 nanodomains. It was found that the nanodomains with small angle boundaries of atomic-scale width were distributed within the subgrains that constitute the clusters in MgB2 grains. This nanostructural characteristic may be intrinsic in the quenched reaction product of Mg and amorphous B. It makes the nanodomain boundaries not act as barriers to the current percolation path, thus exhibiting no weak-link problem in the MgB2.
Publisher: World Scientific Pub Co Pte Ltd
Date: 08-2005
DOI: 10.1142/S0219581X05003668
Abstract: A new characterization method based on impedance frequency response analysis at different temperatures has been developed to assess and identify the dielectric and semiconductor materials for organic field-effect transistors (OFET). This method can not only characterize simultaneously dielectric and conductive behaviors of materials but also distinguish in idual contributions to electrical conduction or to polarization from layers such as dielectric layer, semiconductor layer, and interfaces in OFET. Two kinds of materials, Urathan and DuPont 5018A as dielectric materials have been used to make a multilayer organic capacitor. It has been observed that Urathan, due to its lower conductivity, non-metallic conduction behavior at high temperature, and lower interfacial resistance, is more suitable as dielectric layer for OFET. Urathan appears an enhancement in conductivity by heating following an Arrhenius law with an activation energy transition from 0.002 to 0.24 eV at ~307 K, which originates from band tail hopping that occurs around the Fermi edge. At ~314 K, a dielectric transition also occurs, which is interpreted as a combination of electron polarization associated to the band tail hopping. The materials were used to fabricate OEFT, which performance was in agreement with that obtained from impedance analysis of the organic capacitor.
Publisher: World Scientific Pub Co Pte Lt
Date: 10-10-1997
DOI: 10.1142/S0217984997001237
Abstract: A bond-and-band model is developed to incorporate the chemical bond and the energy band of nitrides. It is suggested that the symmetrical difference of the tetrahedral bond-structure and the similarity in the energy-band determine the performance of these compounds. The presence of bonding, nonbonding lone-pair and the lone-pair-induced antibonding features are of key importance to these materials. Well acclaimed by existing evidence, this model provided preliminary understanding of the physical properties of some nitrides and oxides and particularly, some insight into the origins of the N-enhanced magnetization, the blue-shift in nitride and oxide light emitting as well as the ultrahard and super elastic materials.
Publisher: IOP Publishing
Date: 09-07-2003
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B922677J
Abstract: The ability of a catalyst to accept or donate charge is the key to the process of catalytic reaction. However, the determination of the catalytic nature of a specimen as yet remains a great challenge. Here we report an effective yet simple method for this purpose based on the tight binding theory considerations and XPS monitoring of the evolution of valence and core electrons upon alloy formation. Firstly, we measured the valence and core band charge density of the constituent elements of Cu, Ag, and Pd and then the respective states upon alloy formation. A subtraction of the resultant spectrum of the alloy by the composed elemental spectra gives the residual that shows clearly the occurrence of charge trapping or polarization. We found that the valence and the core electrons of the CuPd alloy shift positively to deeper energies, opposite to the occurrences in the AgPd alloy. Findings clarify for the first time that CuPd serves as an acceptor due to quantum trapping and the AgPd as a donor because of charge polarization, which also explain why AgPd and CuPd perform very differently as important catalysts.
Publisher: Springer Science and Business Media LLC
Date: 07-2006
Publisher: World Scientific Pub Co Pte Lt
Date: 20-02-1997
DOI: 10.1142/S021798499700027X
Abstract: In order to quantify the behaviour of surface electrons on O-chemisorbed metal surface, as observed wtith STM and STS, we developed a model on nonuniform electrical potential barrier. The new modelling approach contains: (1) the elastic potential, the spatial variation and the energy dependence of the inelastic d ing are unified by the electronic distribution (2) the O-induced spatial-localisation and the nonuniformity in energy-state are taken into effect (3) the single-variable parameterised functions simplify the numerical optimisation and ensure the uniqueness in solutions. Therefore, crystal structure models can be judged by comparing the shapes of the crystal-dependent-z 0 (E) profiles that exhibit joint features of topography and spectroscopy.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP00648E
Abstract: From the image, it is observed that salt hydration increases the critical pressures for the liquid–VI–VII phase transitions in the Hofmeister series order in terms of electronegativity difference Δ η and anion radius R .
Publisher: Wiley
Date: 03-05-2022
Abstract: Electrocatalysts for high-rate hydrogen evolution reaction (HER) are crucial to clean fuel production. Nitrogen-rich 2D transition metal nitride, designated "nitridene", has shown promising HER performance because of its unique physical/chemical properties. However, its synthesis is hindered by the sluggish growth kinetics. Here for the first time using a catalytic molten-salt method, we facilely synthesized a V-Mo bimetallic nitridene solid solution, V
Publisher: Elsevier BV
Date: 09-2011
Publisher: AIP Publishing
Date: 06-04-1998
DOI: 10.1063/1.121158
Abstract: Correlation between chemical bonds, energy bands, and the corresponding properties of oxides and nitrides is established. It is proposed that an oxygen or nitrogen atom can hybridize and form a tetrahedron with its four neighbors through bonding orbitals and nonbonding lone pairs. As a result, the energy states of the host material are modified with four additional features, namely, sp3-hybrid bonding, nonbonding (lone pair), antibonding (dipole), and hole states. Therefore, oxygen and nitrogen possess the special ability of not only enlarging the band gap by hole production but also adding an antibonding subband above the Fermi level.
Publisher: World Scientific Pub Co Pte Lt
Date: 04-1998
DOI: 10.1142/S0218625X98000839
Abstract: Incorporating the bond-to-band and the potential barrier model [J. Phys. Chem. Solids58, 903 (1997) J. Phys.: Cond. Matt.27, 5823 (1997)] into the existing database reveals that the O-Ru(0001) triphase results from the formation of O -1 , hybridized O -2 and the addition of a virtual bond, respectively. Oxygen is located at the center of a tetrahedron, forming a Ru 4 O cluster. Initially ( /4 ML), the Ru 4 O ( O -1 + Ru + + 3Ru dipole) forms, retaining C 3v symmetry. Then (1/2 ML), the Ru 4 O develops into a Ru 2 O ( O -2 + 2Ru + + 2Ru dipoles) by forming another bond with a surface Ru atom as a result, a dipole-ion pairing row forms. Finally (1.0 ML), a virtual bond [2Ru(dipoles) + ] forms by redistributing the dipole electrons this process not only reduces the dipole moment but also narrows the antibond subband. The first layer spacing depends upon bond geometry and the second layer spacing contracts due to charge redistribution.
Publisher: Elsevier BV
Date: 09-2015
Publisher: World Scientific Pub Co Pte Lt
Date: 10-10-1997
DOI: 10.1142/S0217979297001490
Abstract: It is shown that the VLEED, furnished with appropriate modelling approaches, is able to reveal comprehensive information about the details of a surface. Constructing Brillouin zones from the critical positions on the angular-resolved VLEED spectra yields information about valence bands and in-plane reconstruction of the O-Cu(001) surface. Decoding the fine-structure features with new models [J. Phys. Chem. Solids58 903 (1997) and J. Phys.: Condens. Matt., C9, 5823 (1997)] rewards us with consistent understanding of the bond formation and its consequences. It is interpreted that the bond forming results in the dislocation of surface atoms, the variation of energy states, the nonuniformity and anisotropy of the potential barrier, and the reduction in both work function and inner potential of the surface.
Publisher: American Chemical Society (ACS)
Date: 17-09-2013
DOI: 10.1021/JZ401380P
Abstract: The specific-heat difference between the O:H van der Waals bond and the H-O polar-covalent bond and the Coulomb repulsion between electron pairs on adjacent oxygen atoms determine the angle-length-stiffness relaxation dynamics of the hydrogen bond (O:H-O), which is responsible for the density and phonon-stiffness oscillation of water ice over the full temperature range. Cooling shortens and stiffens the part of relatively lower specific-heat, and meanwhile lengthens and softens the other part of the O:H-O bond via repulsion. Length contraction/elongation of a specific part always stiffens/softens its corresponding phonon. In the liquid and in the solid phase, the O:H bond contracts more than the H-O elongates, hence, an O:H-O cooling contraction and the seemingly "regular" process of cooling densification take place. During freezing, the H-O contracts less than the O:H elongates, leading to an O:H-O elongation and volume expansion. At extremely low temperatures, the O:H-O angle stretching lowers the density slightly as the O:H and the H-O lengths change insignificantly. In ice, the O-O distance is longer than it is in water, resulting in a lower density, so that ice floats.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CP00060D
Abstract: Artificial undercoordination of Rh atoms at a surface is indeed fascinating. It not only generates unusual energy states, but also differentiates the processes of catalytic reaction and growth nucleation at such atomic sites from those proceeding at a flat surface. Recent findings have stimulated the need a better understanding of the mechanism behind these observations. An X-ray photoelectron differential spectroscopy (XPDS) study reported herein reveals that the undercoordinated Rh atoms at step edges and the nearby missing-row vacancies generate two extra states in the 3d(5/2) band. These findings confirm theoretical [C. Q. Sun, Prog. Solid State Chem., 2007, 35, 1] expectations that the shorter and stronger bonds between undercoordinated atoms cause the local quantum entrapment of the core charge and the polarization of the otherwise conducting s-electrons by the densely and deeply trapped core electrons. Therefore, the XPDS resolved low-energy component arises from quantum entrapment, while the high-energy one arises from potential screening by polarization.
Publisher: Informa UK Limited
Date: 2003
Publisher: American Vacuum Society
Date: 27-06-2002
DOI: 10.1116/1.1486227
Abstract: Nanocomposite amorphous carbon films such as a-C:Al, a-C:Ti, and a-C:Si have been prepared using a filtered cathodic vacuum arc technique. The films were characterized using x-ray photoelectron spectroscopy (XPS), atomic force microscopy, surface profilometry, a nanoindenter, and Raman spectrometry. It was found that metal contents in the films deviate from the target depending on the constituent element, which is attributed to the effect of dynamic balance deposition. XPS results revealed the presence of a carbide phase in a-C:Ti and a-C:Si but not in a-C:Al nanocomposite carbon films. Incorporating metal into amorphous carbon films significantly reduces the compressive stress but maintains the relative high hardness and Young’s modulus.
Publisher: AIP Publishing
Date: 06-08-2007
DOI: 10.1063/1.2766860
Abstract: The authors have computationally designed ultraincompressible materials, namely, rhenium carbide, in the WC and NiAs structures with a very high shear modulus. The corresponding calculated bulk modulus is comparable with that of diamond. Especially for the WC-typed rhenium carbide (ReC), the incompressibility along the c axis is demonstrated to exceed the linear incompressibility of diamond. The unique mechanical properties would make it suitable for applications under extreme conditions.
Publisher: IOP Publishing
Date: 30-07-2003
Publisher: Elsevier BV
Date: 02-2013
Publisher: Elsevier BV
Date: 07-2014
Publisher: American Chemical Society (ACS)
Date: 08-01-2018
Abstract: We resolved the O:H-O bond transition from the mode of ordinary water to its hydration in terms of its phonon stiffness (vibration frequency shift Δω), order of fluctuation (line width), and number fraction (phonon abundance), f
Publisher: Elsevier BV
Date: 02-2009
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.JCIS.2019.03.097
Abstract: Fabrication of high-performance electrodes from waste biomass has attracted increasing attention among the energy storage and conversion field. In this work, we have synthesized nitrogen-doped activated carbon by a simultaneous pyrolysis/activation method from waste bones. It is found that the specific surface area and pore structure of as-synthesized carbon depends on the carbonization temperature (500-800 °C), and the highest specific surface area is 1522 m
Publisher: Wiley
Date: 09-2008
Publisher: Elsevier BV
Date: 08-2005
Publisher: Elsevier BV
Date: 08-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6RA28335G
Abstract: Via separating the H-bonded neighbour molecules of centrally four-coordinated water molecules from other molecules in outer cages, the calculations discover these two regions interact competitively with the central molecule.
Publisher: AIP Publishing
Date: 11-2001
DOI: 10.1063/1.1406551
Abstract: Heat-flow changes of La1−xCaxMnO3+δ (x=0.25, 0.33, and 0.375) magnetoresistive oxides at their Curie temperatures have been detected using differential scanning calorimetry in the temperature range from 173 to 293 K. However, the transition does not occur in the s les of x=0.125 and 0.5. It was found that the heat flow reflected the transition behavior and the enthalpy change of the transition decreased as the transition temperature increased. These results indicate that the La1−xCaxMnO3+δ oxides (x=0.25, 0.33, and 0.375) undergo an endothermic phase transition from a low-temperature ferromagnetic metal to a high-temperature paramagnetic insulator. It is assumed that the transition is strongly associated with a local structure change, which is correlated with the metal–insulator transition.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CY00109D
Publisher: Elsevier BV
Date: 08-2011
Publisher: AIP Publishing
Date: 05-11-2004
DOI: 10.1063/1.1805715
Abstract: We have determined both the effective masses and the barrier heights for electrons and holes in pure SiO2 and lightly nitrided oxides with various nitrogen concentrations up to 4.5 at %. In contrast to previous studies which were usually carried out by assuming a value for either the effective mass or the barrier height, this study does not make such an assumption. The approach is proven to be reliable by examining the result for the well-studied pure SiO2 thin films. It is observed that with the increase of the nitrogen concentration the effective masses increase while both the barrier heights and the energy gap decrease.
Publisher: American Chemical Society (ACS)
Date: 18-12-2003
DOI: 10.1021/JP0372946
Publisher: Elsevier BV
Date: 05-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8CP06910G
Abstract: Charge injection in terms of protons, lone pairs, cations and anions by acid and base solvation mediates the HB network and properties of Lewis solutions through H↔H fragilization, O:⇔:O compression and polarization, ionic polarization and hydrating H 2 O dipolar screen shielding, anion–anion repulsion, compressed solvent H–O bond elongation and undercoordinated solute H–O bond contraction.
Publisher: Elsevier BV
Date: 09-2001
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TA06628C
Abstract: During the process of hydrogen generation via photocatalytic water splitting, solute ions may be adsorbed on the surface of the graphitic carbon nitride (g-C 3 N 4 ) monolayer, modifying its electronic and optical performances, as well as its redox ability due to chemical bond relaxation.
Publisher: Springer Science and Business Media LLC
Date: 1999
Publisher: Elsevier BV
Date: 09-2008
Publisher: AIP Publishing
Date: 15-01-2007
DOI: 10.1063/1.2426377
Abstract: The microstructure, magnetic, and optical properties of Mn-doped ZnO films have been examined. It has been found that Mn doping could improve the growth of ZnO (002) orientation without Mn oxide formation. All the films are ferromagnetic with a Curie temperature of above 350K. The ferromagnetism comes from the ferromagnetic interaction activated by oxygen vacancies between the Mn ions that replace Zn ions, but not from Mn oxide impurities. At an atomic fraction of 2.2% Mn, the average moment per Mn ion reaches a maximum of 0.55μB. With the further increase of Mn atomic fraction, the average moment per Mn ion decreases because the antiferromagnetic energy is lower than the ferromagnetic one due to the reduced distance between the adjacent Mn ions. Meanwhile, the optical band gap value increases from 3.120to3.162eV with the increase of Mn atomic fraction from 0% to 7.5%.
Publisher: Elsevier BV
Date: 12-2004
Publisher: Wiley
Date: 27-04-2015
Abstract: By using combination of bond-order-length-strength (BOLS) correlation, the tight-binding (TB) approach, and zone-selective photoelectron spectroscopy (ZPS), we were able to resolve local bond relaxation and the associated 4f7/2 core-level shift of Au atomic clusters, Au(100, 110, 111) skins, and Au foils exposed to ozone for different lengths of time. In addition to quantitative information, such as local bond length, bond energy, binding-energy density, and atomic cohesive energy, the results confirm our predictions that bond-order deficiency shortens and stiffens the bond between undercoordinated atoms, which results in local densification and quantum entrapment of bonding electrons. The entrapment perturbs the Hamiltonian, and hence, shifts the core-level energy accordingly. ZPS also confirms that oxidation enhances the effect of atomic undercoordination on the positive 4f7/2 energy shift, with the associated valence electron polarization contributing to the catalytic ability of undercoordinated Au atoms.
Publisher: SAGE Publications
Date: 12-01-2018
Abstract: We formulated the composition and temperature dependence of the Si and Si
Publisher: Wiley
Date: 14-11-2016
DOI: 10.1002/JRS.5060
Publisher: Wiley
Date: 27-10-2006
DOI: 10.1002/JBM.A.31001
Abstract: Polypyrrole was electrochemically synthesized onto a gold electrode in the presence of sodium p-toluenesulfonate (TSNa) as the key dopant. Under the optimal synthesis condition, the surface morphology of PPy/TSNa was tailored and exhibited a nano-tentacle structure. The resulting rough and fuzzy morphology greatly enhanced the apparent surface area as well as the polymer film conductivity. Adenosine triphosphate (ATP) was then incorporated in the structure by subsequent ion exchanging. This procedure could be envisaged as pseudo-molecular templating to eliminate several shortcomings associated with physical templating. Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopy were conducted to investigate the incorporation of ATP. The pronounced rough surface of PPy/TSNa provided a higher density of active sites for ATP binding. The resulting PPy/ATP film exhibited a high charged capacity and lower impedance compared to the bare gold electrode. ATP remained stable in the PPy film however, a negative bias to the electrode stimulated the conducting polymer to release ATP. This concept could serve as a mechanism for drug delivery and biosensing applications.
Publisher: AIP Publishing
Date: 2016
DOI: 10.1063/1.4940768
Abstract: The thermal conductivity of Si/Ge core-shell nanowires (CSNWs) is investigated on the basis of atomic-bond-relaxation consideration and continuum mechanics. An analytical model is developed to clarify the interface bond relaxation of Si/Ge CSNWs. It is found that the thermal conductivity of Si core can be modulated through covering with Ge epitaxial layers. The change of thermal conductivity in Si/Ge CSNWs should be attributed to the surface relaxation and interface mismatch between inner Si nanowire and outer Ge epitaxial layer. Our results are in well agreement with the experimental measurements and simulations, suggesting that the presented method provides a fundamental insight of the thermal conductivity of CSNWs from the atomistic origin.
Publisher: AIP Publishing
Date: 28-07-2014
DOI: 10.1063/1.4891558
Abstract: In this paper, we clarified a robust mechanism of magnetism generated by excess electrons captured by edge-quantum well of diamagnetic armchair edges. Consistency between density functional theory calculations and electron cyclotron resonance experiments verified that: (1) Multi-layer armchair nanoribbons are stable with proper amounts of excess electrons which can provide net spin (2) Since under-coordination induces lattice relaxation and potential well modulation, electrons tend to be trapped at edges and (3) Neither large amount of excess electrons nor positive charges can induce magnetism. This work shed light on the development of graphene devices in its magnetic applications.
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 2018
Publisher: American Physical Society (APS)
Date: 09-11-2006
Publisher: American Chemical Society (ACS)
Date: 18-08-2007
DOI: 10.1021/JP0727087
Publisher: American Chemical Society (ACS)
Date: 18-07-2012
DOI: 10.1021/JP304366Z
Abstract: Incorporating the tight-binding theory and the bond order-length-strength (BOLS) correlation into the X-ray photoelectron spectra of Ag(111) and (100) surfaces and the Auger electron spectra of Ag nanoparticles deposited on Al2O3 and CeO2 substrates has led to quantitative information of the 3d5/2 and the valence binding energies of an isolated Ag atom and their shifts upon bulk, defect, surface, and nanocrystal formation. It is clarified that the globally positive energy shifts originate from the undercoordination-induced Goldschmidt-Pauling bond contraction and the associated local quantum entrapment and the heterocoordination-induced bond nature alteration at the particle-substrate interfaces. Perturbation to the Hamiltonian by atomic ill-coordination dictates the energy shift that is proportional to the bond energy at equilibrium. Theoretical reproduction of the measured spectroscopic data derived that the 3d5/2 energy of an isolated Ag atom shifts from 363.02 to 367.65 eV and the valence band center from 0.36 to 8.32 eV upon bulk formation. The extended Wagner plots revealed the coefficients of valence recharging and potential screening to be 1.21 and 1.56 for Ag interacting with Al2O3 substrate and 1.15 and 1.50 for Ag with CeO2, respectively. Exercises exemplify the enhanced capabilities of XPS and AES in determining quantitative information regarding the evolution of the local bond length, bond energy, binding energy density, and atomic cohesive energy, with the coordination and chemical environment.
Publisher: Elsevier BV
Date: 02-2009
Publisher: American Vacuum Society
Date: 03-2004
DOI: 10.1116/1.1651108
Abstract: The effect of plasma fluorination on the band gap, 2p core-level energy, and the dielectric behavior of porous silicon (PS) prepared under constant conditions has been examined using Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, photoluminescence, and reflection. It has been found that with increasing extent of fluorination, the band gap expands, and the 2p level and the dielectric constant drop down substantially compared with those of the as-grown PS, being quite similar to the effect of particle size reduction. These findings could be interpreted as the fluorination-induced crystal field enhancement and the valence charge repopulation of silicon. The surface fluorination may provide an effective method for tuning the optical and dielectric properties of nanometric silicon.
Publisher: IOP Publishing
Date: 03-03-2000
Publisher: Wiley
Date: 15-11-2022
Abstract: Photocatalytic performance can be optimized via introduction of reactive sites. However, it is practically difficult to engineer these on specific photocatalyst surfaces, because of limited understanding of atomic‐level structure‐activity. Here we report a facile sonication‐assisted chemical reduction for specific facets regulation via oxygen deprivation on Bi‐based photocatalysts. The modified Bi 2 MoO 6 nanosheets exhibit 61.5 and 12.4 μmol g −1 for CO and CH 4 production respectively, ≈3 times greater than for pristine catalyst, together with excellent stability/reproducibility of ≈20 h. By combining advanced characterizations and simulation, we confirm the reaction mechanism on surface‐regulated photocatalysts, namely, induced defects on highly‐active surface accelerate charge separation/transfer and lower the energy barrier for surface CO 2 adsorption/activation/reduction. Promisingly, this method appears generalizable to a wider range of materials.
Publisher: American Chemical Society (ACS)
Date: 06-08-2003
DOI: 10.1021/BM030003E
Abstract: We describe here a new approach to construct a multilayer enzyme olyelectrolyte film on a structured transparent indium-tin oxide (ITO) covered glass electrode surface as micropattern, on which two different types of enzyme distributed laterally on one common substrate without interference. The multilayer film was prepared by alternate electric field directed layer-by-layer assembly deposition and alternate deposition of different redox enzymes and polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA) onto the site-selective ITO glass electrode surface. The cyclic voltammogram, obtained from the ITO glass electrode modified with the glucose oxidase (GO(X))/PDDA and catalase (CA(T))/PDDA multilayers, revealed that the bioelectrocatalytic response is directly correlated to the number of deposition bilayers. From the analysis of cyclic voltammetric characterization, the coverage of catalytically active enzymes per enzyme/PDDA bilayer during the multilayer formation was homogeneous, which demonstrates that the multilayer is constructed in a spatially ordered manner. Also, from the atomic force microscopy and Brewster angle microscopy measurements, more information of the multilayer constructed by different methods on the modified electrode surface is obtained and compared. This fabrication technique is simple and would be applicable to the construction of a thickness- and area-controlled biopattern composed of multi-enzymes as well as multiple biomaterials.
Publisher: Royal Society of Chemistry (RSC)
Date: 20-08-2014
DOI: 10.1039/C4CP02516D
Abstract: Consistency in experimental observations, numerical calculations, and theoretical predictions have revealed that the skins of water and ice share the same attribute of supersolidity characterized by an identical H-O vibration frequency of 3450 cm(-1). Molecular undercoordination and inter-electron-pair repulsion shortens the H-O bond and lengthens the O:H nonbond, leading to a dual process of nonbonding electron polarization. This relaxation-polarization process enhances the dipole moment, elasticity, viscosity, and thermal stability of these skins with a 25% density loss, which is responsible for the hydrophobicity and toughness of the water skin and results in the slippery behavior of ice.
Publisher: Wiley
Date: 29-08-2019
Abstract: Our recent work ( J. Phys. Chem. Lett . 2019 , 10 , 2378) reported the discovery of the abnormal pnictogen dual aromaticity (π and σ) in cyclo ‐N 5 − , which makes the anion unstable in nature but confers enhanced stability in sufficiently acid solution. Herein, we present systematic quantum calculations on the structures, energetics and dynamics of the pentazolate salt and metal pentazolate hydrates, focusing on the mechanism and functionality of the pnictogen dual aromaticity in these crystals, which are verified by experiments. We find that owning a net charge of − e is crucial to the formation of the dual aromaticity and the stabilization of the cyclo ‐N 5 − . The competition between the dual aromaticity and the proton affinity drives the cyclo ‐N 5 − to be unreactive to acid and remain unprotonated in these crystals. We decompose the crystal packing effect into pure mechanical compression and interspecies nonbonding interactions, and figure out that the type and number of the adjacent counterions of the cyclo ‐N 5 − anion, instead of the compression effect, accounts for the protonation state reversion in the vacuum and in the crystal. The current work supports our original conclusion ( Science 2018 , 359 , eaas8953) and is expected to provide compelling evidence against the current debate on the cyclo ‐N 5 − stability ( Science 2018 , 359 , eaao3672 J. Phys. Chem. Lett . 2018 , 9 , 7137 J. Am. Chem. Soc . 2019 , 141 , 2984).
Publisher: Wiley
Date: 27-04-2007
Publisher: Elsevier BV
Date: 2001
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: Elsevier BV
Date: 08-2005
Publisher: AIP Publishing
Date: 20-08-2001
DOI: 10.1063/1.1394946
Abstract: A single band of photoluminescence (PL) has been detected at room temperature from the Pb(ZrxTi1−x)O3 (x=0–1.0) surface. The intense and stable PL band covers 475±50 nm (or 2.67±0.25 eV) wavelengths and the corresponding photoexcitation (PE) band is in the range of 305±45 nm. It is found that changing the x value causes a negligible shift of the PL and PE peaks, and the light emission is subject to the Pb presence. The minimal lifetime of the excited photons was found to be 0.03 ms at x=0.5 and the maximum lifetime of 0.60 ms can be achieved by either decreasing or increasing the x values.
Publisher: Springer Science and Business Media LLC
Date: 09-09-2015
DOI: 10.1038/SREP13655
Abstract: Regelation, i.e., ice melts under compression and freezes again when the pressure is relieved, remains puzzling since its discovery in 1850’s by Faraday. Here we show that hydrogen bond (O:H-O) cooperativity and its extraordinary recoverability resolve this anomaly. The H-O bond and the O:H nonbond possesses each a specific heat η x (T/Θ Dx ) whose Debye temperature Θ Dx is proportional to its characteristic phonon frequency ω x according to Einstein’s relationship. A superposition of the η x (T/Θ Dx ) curves for the H-O bond (x = H, ω H ~ 3200 cm −1 ) and the O:H nonbond (x = L, ω L ~ 200 cm −1 , Θ DL = 198 K) yields two intersecting temperatures that define the liquid/quasisolid/solid phase boundaries. Compression shortens the O:H nonbond and stiffens its phonon but does the opposite to the H-O bond through O-O Coulomb repulsion, which closes up the intersection temperatures and hence depress the melting temperature of quasisolid ice. Reproduction of the T m (P) profile clarifies that the H-O bond energy E H determines the T m with derivative of E H = 3.97 eV for bulk water and ice. Oxygen atom always finds bonding partners to retain its sp 3 -orbital hybridization once the O:H breaks, which ensures O:H-O bond recoverability to its original state once the pressure is relieved.
Publisher: American Chemical Society (ACS)
Date: 13-05-2021
DOI: 10.1021/JACS.1C03135
Publisher: MDPI AG
Date: 26-12-2017
DOI: 10.3390/MA11010033
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.BIOS.2008.06.003
Abstract: Pt-Pb nanowire array was directly synthesized by electrochemical deposition of Pt-Pb alloy into the pores of microporous polycarbonate template and subsequent chemical etching of the template. The morphology and the composition of the Pt-Pb nanowires were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Cyclic voltammetry (CV) was used to evaluate the electrochemical performance of the Pt-Pb nanowire array electrode (Pt-PbNAE). Direct glucose oxidation on Pt-PbNAE was investigated in detail by discussing the effect of the structure and materials of the electrode on electrocatalytic oxidation of glucose. As a result, we found that the Pt-PbNAE with a three-dimensional structure exhibited high electrocatalytic activity to glucose oxidation in neutral condition and could be used for the development of nonenzymatic glucose sensor. To effectively avoid the interference coming from ascorbic acid, a negative potential of -0.20V was chosen for glucose detection, and the sensitivity of the sensor to glucose oxidation was 11.25 microAmM(-1)cm(-2) with a linearity up to 11 mM, and a detection limit of 8 microM (signal-to-noise ratio of 3).
Publisher: American Chemical Society (ACS)
Date: 16-07-2003
DOI: 10.1021/JP035070H
Publisher: Jenny Stanford Publishing
Date: 30-03-2016
DOI: 10.1201/B19904-11
Publisher: Elsevier BV
Date: 06-2006
Publisher: Elsevier BV
Date: 09-1989
Publisher: Qeios Ltd
Date: 27-08-2021
DOI: 10.32388/JH9NY0
Publisher: American Scientific Publishers
Date: 08-2009
Abstract: The dynamics of the monopole collective vibration of a Leonard-Jones 147-atom cluster has been examined using molecular dynamics simulation. It is found that the process of energy release of the vibrating cluster depends on the extent of the initial atomic dislocation stimulus. A relatively larger-scale perturbation will cause a faster decay of the vibration magnitude despite the higher potential and kinetic energy compared to the vibration stimulated by a small-scale dislocation stimulus. Due to the compression by the outermost shells, the potential energy of atoms in the inner shells increases while that of the outer shells decreases during the process of energy release until equilibrium state. Findings provide hitherto insight into the dynamics of energy releases of an atomic cluster induced by a sudden dislocation stimulus.
Publisher: Qeios Ltd
Date: 17-06-2021
DOI: 10.32388/FO6KAP
Publisher: American Chemical Society (ACS)
Date: 19-07-2010
DOI: 10.1021/JP104204Y
Publisher: Elsevier BV
Date: 05-2017
Publisher: Informa UK Limited
Date: 02-10-2018
Publisher: Elsevier BV
Date: 12-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP03587A
Abstract: Doping with early transition metals leads to the rising of the energy level of the valence band center by about 0.2 eV and declining of the energy level of the conductor band center by about 0.8 eV.
Publisher: Elsevier BV
Date: 2000
Publisher: AIP Publishing
Date: 08-07-2003
DOI: 10.1063/1.1591070
Abstract: In this work, we report the discovery of a vortex pinning source: semicrystalline defect wells in self-aligned nanostructured MgB2. It is demonstrated that these aperiodic regions trap numerous crystal defects migrating along nanodomain boundaries during self-alignment and act as intense vortex pinning centers that significantly enhance the high-field performance of MgB2. This suggests that the density of trapped defects in the wells is much greater than that found in other vortex pinning sources.
Publisher: American Chemical Society (ACS)
Date: 21-09-2002
DOI: 10.1021/JP025868L
Publisher: Elsevier BV
Date: 10-2013
Publisher: Elsevier BV
Date: 03-2002
Publisher: AIP Publishing
Date: 15-02-1989
DOI: 10.1063/1.342934
Abstract: The Fe nitride films were easily produced by facing targets sputtering (FTS). The structures and magnetic properties of the films depend on the reactive pressure (PN) and dc substrate biasing voltage (Vb). α-Fe, α″-Fe16N2, γ′-Fe4N, ε-Fe3N, and ζ-Fe2N as well as the amorphous FeN phase have been produced at the PN ranges of 0–8×10−3 Torr. The magnetic moment per iron atom increases with PN until PN=1.0 mTorr at which the α′-Fe16N2 phase appears with the coercive force Hc=103 A/m, susceptibility χm=161, and μS=2.85 μB. The relation between conductivity and temperature σ-T indicates that Fe nitride films resemble a semiconductor. The Curie temperature of these films is reduced with the increase of PN. Magnetic relaxation phenomena were observed in the vicinity of 540 °C.
Publisher: American Chemical Society (ACS)
Date: 16-02-2012
DOI: 10.1021/CR200428M
Publisher: Elsevier BV
Date: 10-2014
Publisher: American Physical Society (APS)
Date: 12-01-2004
Publisher: Springer Science and Business Media LLC
Date: 30-04-2012
Publisher: Elsevier BV
Date: 06-2008
Publisher: Elsevier BV
Date: 06-2018
Publisher: American Chemical Society (ACS)
Date: 10-10-2008
DOI: 10.1021/JP8063068
Publisher: World Scientific Pub Co Pte Lt
Date: 10-2001
DOI: 10.1142/S0218625X01001385
Abstract: Ti thin film is widely used as a diffusion barrier to impede the Al/Cu migrating to the Si substrate in the applications requiring high temperature processes such as high temperature sputtering and reflow developed for via-filling. To improve the bottom coverage without losing the excellent diffusion blockage and other electronic properties, the ionized metal plasma (IMP) deposition technique has been developed. This method has better control of the angular distribution on the substrate, and thus has been used to deposit Ti as diffusion barriers for the subquarter micron device applications. However, the formation mechanism of the epitaxy Ti thin film deposited by ionic metal plasma deposition is not clear. In this work, the epitaxy Ti thin film has been characterized by the transmission electron microscope. The mechanism of the epitaxy Ti thin film formation and also the crystallographic relationship between the Ti and Al thin films in the IMP deposition have been analyzed in detail. The results show that the lattice image of the Ti layer in the s le as deposited has a square-block-like structure with the c axis perpendicular to the interfaces. This structure has anisotropic diffusion properties that can retard the diffusion of Al across the Ti layer in the initial stage of the high temperature Al sputtering or reflow processes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TA10981J
Publisher: Science China Press., Co. Ltd.
Date: 09-2019
DOI: 10.1360/TB-2019-0220
Publisher: Elsevier BV
Date: 06-2018
Publisher: The Electrochemical Society
Date: 2002
DOI: 10.1149/1.1505741
Publisher: Royal Society of Chemistry (RSC)
Date: 08-03-2002
DOI: 10.1039/B109825J
Publisher: Elsevier BV
Date: 02-2019
Publisher: Elsevier BV
Date: 07-2016
Publisher: Elsevier BV
Date: 11-2010
Publisher: Elsevier BV
Date: 02-2017
Publisher: Springer Science and Business Media LLC
Date: 27-03-2008
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.BIOS.2008.03.004
Abstract: Multi-wall carbon nanotubes (MWNTs) functionalized with amino groups were prepared via silane treatment using 3-aminopropyltrimethoxysilane (APS) as a silane-coupling agent. The resultant amino terminated MWNTs (AMWNTs) were applied to construct glucose biosensors with IO(4)(-)-oxidized glucose oxidase (IO(4)(-)-oxidized GOx) through the layer-by-layer (LBL) covalent self-assembly method without any cross-linker. Scanning electron microscopy (SEM) indicated that the assembled AMWNTs were almost in a form of small bundles or single nanotubes, and the surface density increased uniformly with the number of GOx/AMWNTs bilayers. From the analysis of voltammetric signals, a linear increment of the coverage of GOx per bilayer was estimated. The resulting biosensor showed excellent catalytic activity towards the electroreduction of dissolved oxygen at low overvoltage, based on which glucose concentration was monitored conveniently. The enzyme electrode exhibited good electrocatalytic response towards the glucose and that response increased with the number of GOx/AMWNTs bilayers, suggesting that the analytical performance such as sensitivity and detection limit of the glucose biosensors could be tuned to the desired level by adjusting the number of deposited GOx/AMWNTs bilayers. The biosensor constructed with four bilayers of GOx/AMWNTs showed high sensitivity of 7.46 microA mM(-1)cm(-2) and the detection limit of 8.0 microM, with a fast response less than 10s. Because of relative low applied potential, the interference from other electro-oxidizable compounds was minimized, which improved the selectivity of the biosensors. Furthermore, the obtained enzyme electrodes also showed remarkable stability due to the covalent interaction between the GOx and AMWNTs.
Publisher: American Physical Society (APS)
Date: 16-02-2007
Publisher: Elsevier BV
Date: 12-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B915099D
Abstract: Synthesis of metal molybdates (XMoO(4), X = Ca, Sr, Ba) have received much attention recently because of their interesting structural and luminescent properties. Here novel erythrocyte-like CaMoO(4) hierarchical nanostructures are synthesized via a simple surfactant-free hydrothermal route. The formation of the calcium molybdate erythrocytes is controllable through adjusting the fundamental experimental parameters including reaction time, temperature and DMAc to H(2)O ratio. The as-synthesized products are characterized using X-ray powder diffraction, scanning electron microscopy, Brunauer-Emmett-Teller and transmission electron microscopy. The results show that the nucleation and growth of the novel erythrocyte-like CaMoO(4) hierarchical nanostructures are governed by an oriented attachment growth mechanism. The luminescent properties of the CaMoO(4) erythrocytes are then studied using a spectrophotometer and the erythrocyte-like CaMoO(4) nanostructures display a strong blue emission. This study provides an easy surfactant-free synthetic route for the controllable construction of inorganic materials with high hierarchy in the absence of any surfactants.
Publisher: Wiley
Date: 09-08-2016
DOI: 10.1002/QUA.25223
Publisher: Elsevier BV
Date: 09-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2NR11605G
Abstract: With structural miniaturization down to the nanoscale, the detectable quantities of solid materials no longer remain constant but become tunable. For the II-VI semiconductors ex le, the band gap expands, the elastic modulus increases, the melting point drops, and the Raman optical phonons experience red shift associated with creation of low frequency Raman acoustic modes that undergo blue shift with decreasing the dimensional scale. In order to understand the common origin of the size dependency of these seemingly irrelevant properties, we formulated these quantities for CdS, ZnS, and CdSe semiconductors from the perspectives of bond order-length-strength correlation and the local bond averaging approach. Consistency between the theory predictions and the measured size dependence of these quantities clarified that the undercoordination-induced local strain and quantum entrapment and the varied fraction of undercoordinated atoms of the entire solid correlate these quantities and dominate their size effect.
Publisher: AIP Publishing
Date: 31-07-2023
DOI: 10.1063/5.0160714
Abstract: Based on the correlation between Raman shift and bond parameters, and further combined with experimental values of the Raman shift composition effect, the relationship between the composition and bond parameters of the 2D-M1−xM′xX2 and 2D-MX′2xX2(1−x) alloy materials was established. Numerical reproduction of the measurements clarified that the host atom phonons involved interaction with all of its z neighbors, whereas the doping atom phonon only involved interaction with a dimer. The doping of large atoms resulted in an elongation of the bond length, an increase in the equivalent coordination number, and enhancement of the binding energy. The doping of small atoms led to a contraction of the bond length, a decrease in the equivalent coordination number, and a weakening of binding energy. By quantifying the relationship between composition and bond parameters from Raman shifts, a deep understanding of two-dimensional alloy properties can be achieved.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1RA00298H
Publisher: Elsevier BV
Date: 12-2016
Publisher: American Scientific Publishers
Date: 08-2014
Publisher: Elsevier BV
Date: 10-2012
Publisher: World Scientific Pub Co Pte Lt
Date: 06-2000
DOI: 10.1142/S0218625X00000312
Abstract: From the perspective of sp orbital hybrid bonding and its consequence on the behavior of valence electrons, new insight is presented into the nature of oxygen-derived features in the valence band and above of metals. It is suggested that the crystal geometry and the surface morphology may vary from surface to surface and from material to material but the oxygen-derived features in energy space are substantially the same in nature. The derived features can be consistently specified as oxygen–metal bonding (-5 to -8 eV), a nonbond lone pair of oxygen (-1 to -2 eV), holes of metal ions (~E F ) and antibonding metal dipole states ( E F ), other than the addition of the 2s or 2p states of the isolated oxygen additives.
Publisher: AIP Publishing
Date: 10-2010
DOI: 10.1063/1.3471818
Abstract: The functional dependence of stress, elastic modulus, melting point, and their interdependence on the identities (bond order, nature, length, and strength) of a representative bond of the specimen has been established for deeper insight into the transition from the conventional Hall–Petch relationship (HPR) to the inverse HPR (IHPR) for nanostructured TiO2. Theoretical reproduction of the observed inverse HPR suggests that the intrinsic competition between the energy-density gain (elastic modulus enhancement) and the cohesive-energy remnant (melting point depression) in the grain boundaries originates and the extrinsic competition between the activation and the inhibition of atomic dislocations activates the IHPR.
Publisher: Royal Society of Chemistry (RSC)
Date: 11-10-2013
DOI: 10.1039/C3CP52149D
Abstract: Gold nanoparticles have been widely used as nanocarriers in gene delivery. However, the binding mechanism between gold nanoparticles and DNA bases remains a puzzle. We performed density functional theory calculations with and without dispersion correction on Au(N)( (N = 13, 55, or 147) nanoparticles in high-symmetry cuboctahedral structures to understand the mechanism of their binding with guanine at the under-coordinated sites. Our study verified that: (i) negative charges transfer from the inner area to the surface of a nanoparticle as a result of the surface quantum trapping effect and (ii) the valence states shift up toward the Fermi level, and thereby participate more actively in the binding to guanine. These effects are more prominent in a smaller nanoparticle, which has a larger surface-to-volume ratio. Additional fragment orbital analysis revealed that: (i) electron donation from the lone-pair orbital of N to the unoccupied orbital of the Au cluster occurs in all complexes (ii) π back-donation occurs from the polarized Au d(yz) orbital to the N p(y)-π* orbital when there is no Au···H-N hydrogen bond, and, (iii) depending on the configuration, Au···H-N hydrogen bonding can also exist, to which the Au occupied orbital and the H-N unoccupied orbital contribute.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CP03919K
Abstract: H–O bond energy governs the P Cx for Na/H 2 O liquid–VI–VII phase transition. Solute concentration affects the path of phase transitions differently with the solute type. Solute–solute interaction lessens the P C2 sensitivity to compression. The P C1 goes along the liquid–VI boundary till the triple phase joint.
Publisher: IOP Publishing
Date: 07-07-1997
Publisher: American Chemical Society (ACS)
Date: 28-11-2011
DOI: 10.1021/JP208248V
Publisher: Elsevier BV
Date: 2020
Publisher: AIP Publishing
Date: 09-2001
DOI: 10.1063/1.1390305
Abstract: It is shown that bond contraction and nonbonding lone-pair interaction dominate at nitride surfaces. The maximum elastic recovery of a nitride surface was found to be 100% under a relatively lower nanoindentation load (& .0 mN) and the hardness of the surface was found to be 100% higher than the bulk value. It is interpreted that the spontaneous bond contraction, estimated at 12%–14%, strengthens the binding energy and hence the hardness and Young’s modulus at the surface. The lone-pair weak interaction claims the responsibility for (i) the high elastic recovery, (ii) the lower Raman frequencies of vibration, and (iii) the existence of critical loads for slide friction or lone-pair broken.
Publisher: Elsevier BV
Date: 06-1997
Publisher: AIP Publishing
Date: 02-2011
DOI: 10.1063/1.3544042
Abstract: Although the physics behind the bulk modulus, B(T,P), as a function of temperature (T) and pressure (P), has been intensively investigated, an atomic scale understanding of this attribute remains a high challenge. Here, we show that the B(T,P) for BaXO3 (X=Ti,Zr,Nb) can be established by connecting the B directly to the bond length and bond energy and their response to the applied T and P in the form of binding energy density, B[E/d3(T,P)]. Besides an estimation of the Debye temperature and single bond energy, outcomes clarified that the thermally softened B arises from bond expansion and bond weakening due to lattice vibration and the mechanically stiffened B results from bond compression and bond strengthening due to mechanical work hardening.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4CP05985A
Abstract: We report density functional theory observations that confirm the presence of predicted DOS features of holes and nonbonding lone pair DOS near the valence band edge of oxygen adsorption on the Ti(0001) surface.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Qeios Ltd
Date: 04-07-2021
DOI: 10.32388/FK57HD
Publisher: AIP Publishing
Date: 12-2007
DOI: 10.1063/1.2819721
Abstract: The effect of nitrogen (N) doping on the behavior of field emission, surface energy and the band structure of strontium titanate (SrTiO3) thin films coated on silicon tip arrays has been examined in detail. Measurements using x-ray photoelectron spectroscopy, ellipsometry, water contact angle and field emission testing revealed that the optimal 50%-nitrogen partial pressure (PN) could improve substantially the threshold field of electron emission of the SrTiO3 films accompanied with narrowed band gap, lowered surface energy and work function and a negative energy shift of the N 1s level from 404 to 396 eV. Results evidence consistently the presence of the nonbonding lone pairs and the lone pair induced antibonding dipoles upon tetrahedron formation which is responsible for the observations. At PN below and above the optimal value physisorption and hydrogen bond likes formation like to occur.
Publisher: AIP Publishing
Date: 07-03-2007
DOI: 10.1063/1.2710265
Abstract: Highly ordered gold nanoparticle multilayer films were achieved conveniently using didodecyldimethylammonium bromide (DDAB) films as a template. The template was produced by casting DDAB chloroform solution onto the surface of a (3-aminopropyl)trimethoxysilane-modified indium tin oxide substrate and then evaporating the organic solvent. Gold nanoparticle multilayer films were prepared by soaking the template in 2.6nm colloidal gold solution for 120min. The well-ordered superlattice structure of the DDAB template and the gold nanoparticle multilayer films was identified by x-ray diffraction. The characterizations of the gold nanoparticle multilayer films by UV-vis spectroscopy, atomic force microscopy, and cyclic voltammerty were described in detail. The application of the as-prepared gold nanoparticle multilayer films in surface-enhanced Raman spectroscopy (SERS) was investigated by using Rhodamine 6G as a probe molecule. It was found that the colloidal gold nanoparticle multilayer films exhibit remarkable enhancement ability and can be used as SERS substrates.
Publisher: Wiley
Date: 11-12-2020
DOI: 10.1002/JRS.5766
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8NR09300H
Abstract: Although single metal atoms (SMAs) have been extensively investigated as unique active sites in single-atom catalysts, the possible active sites of the host catalysts have been unfortunately neglected in previous studies.
Publisher: Elsevier BV
Date: 11-2013
Publisher: Elsevier BV
Date: 2013
Publisher: American Vacuum Society
Date: 05-2007
DOI: 10.1116/1.2723754
Abstract: The field emission of electrons from silicon-tip arrays coated with SrTiO3 thin layers has been investigated. It is found that the emission properties are sensitive to the preparation conditions and the extent of nitrogen doping in the magnetron sputtering. Nitrogen addition could reduce the band gap of the SrTiO3 caps to improve the emission properties significantly with a threshold field of 17V∕μm and the stability of emitted current compared with the uncoated silicon tips. Results demonstrate that SrTiO3 thin films with N addition effectively lower the work function of silicon tips. However, oxygen-rich SrTiO3 exhibits a detrimental effect. Findings are explained in terms of valence-density-state modification by the nonbonding lone pairs and the lone-pair-induced dipoles [W. T. Zheng and C. Q. Sun, Prog. Solid State Chem. 34, 1 (2006)].
Publisher: Elsevier BV
Date: 08-2004
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: American Chemical Society (ACS)
Date: 09-12-2009
DOI: 10.1021/JP908220A
Publisher: Wiley
Date: 03-05-2022
Abstract: Electrocatalysts for high‐rate hydrogen evolution reaction (HER) are crucial to clean fuel production. Nitrogen‐rich 2D transition metal nitride, designated “nitridene”, has shown promising HER performance because of its unique physical/chemical properties. However, its synthesis is hindered by the sluggish growth kinetics. Here for the first time using a catalytic molten‐salt method, we facilely synthesized a V−Mo bimetallic nitridene solid solution, V 0.2 Mo 0.8 N 1.2 , with tunable electrocatalytic property. The molten‐salt synthesis reduces the growth barrier of V 0.2 Mo 0.8 N 1.2 and facilitates V dissolution via a monomer assembly, as confirmed by synchrotron spectroscopy and ex situ electron microscopy. Furthermore, by merging computational simulations, we confirm that the V doping leads to an optimized electronic structure for fast protons coupling to produce hydrogen. These findings offer a quantitative engineering strategy for developing analogues of MXenes for clean energy conversions.
Publisher: Elsevier BV
Date: 09-2003
Publisher: Elsevier BV
Date: 09-2007
Publisher: IOP Publishing
Date: 16-11-2004
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Elsevier BV
Date: 08-2015
Publisher: Springer Singapore
Date: 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CY00013C
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: American Chemical Society (ACS)
Date: 13-04-2015
Abstract: It has long been puzzling that water nanodroplets undergo simultaneously "supercooling" at freezing and "superheating" at melting. Recent progress (Sun et al. J. Phys. Chem. Lett. 2013, 4, 2565, 3238) enables us to resolve this anomaly from the perspective of hydrogen bond (O:H-O) specific heat disparity. A superposition of the specific heat ηx(T) curves for the H-O bond (x = H) and the O:H nonbond (x = L) defines two intersecting temperatures that form the ice/quasi-solid/liquid phase boundaries. Molecular undercoordination (with fewer than four nearest neighbors in the bulk) stretches the ηH(T) curve by raising the Debye temperature ΘDH through H-O bond shortening and phonon stiffening. The ηH(T) stretching is coupled with the ηL(T) depressing because of the Coulomb repulsion between electron pairs on oxygen ions. The extent of dispersion varies with the size of a droplet that prefers a core-shell structure configuration-the bulk interior and the skin. Understandings may open an effective way of dealing with the thermodynamic behavior of water droplets and bubbles from the perspective of O:H-O bond cooperativity.
Publisher: Elsevier BV
Date: 2003
Publisher: American Chemical Society (ACS)
Date: 08-12-2004
DOI: 10.1021/JP045894E
Abstract: An analytical solution shows that a competition between bond order loss and the associated bond strength gain of the lower coordinated atoms near the edge of a surface dictates the mechanics of the surface and, hence, a nanosolid. Bond order loss lowers the activation energy for atomic dislocation, whereas bond strength gain enhances the energy density or mechanical strength in the region near the surface. Therefore, the surface is harder than the bulk interior at temperatures far below the melting point (T(m)), and the surface becomes softer at temperatures close to the surface T(m) that drops because of bond order loss. Matching predictions to measurements reveals that a transition happens to the Hall-Petch relationship for a nanosolid when the effect of bond order loss becomes dominant, and the critical size of the Hall-Petch transition depends intrinsically on the bond nature of the specimen and the ratio of T/T(m), where T is the temperature of operation.
Publisher: Elsevier BV
Date: 05-2008
Publisher: Elsevier BV
Date: 10-2017
Publisher: American Chemical Society (ACS)
Date: 12-06-2008
DOI: 10.1021/JP077598I
Abstract: An approach of local bond average (LBA) has been developed by extending the bond-order-length-strength correlation (Sun, C. Q. Prog. Solid State Chem. 2007 , 35, 1- 159 ) to temperature domain for the mechanism of the thermally driven bond expansion in a solid specimen. It is shown that the detectable quantities of a solid can be connected directly to the bonding identities and the response of the bonding identities to the stimulus of temperature change, being free from using the concepts in classical thermodynamics or hypothetical constants. The success of the LBA approach has been evidenced by fitting the observations from a number of specimens with derived information of atomic cohesive energy, which may go beyond the currently available approaches.
Publisher: American Chemical Society (ACS)
Date: 22-07-2016
Publisher: Elsevier BV
Date: 08-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC14875C
Abstract: CdS-reduced graphene oxide (RGO) composites are successfully synthesized via the microwave-assisted reduction of graphite oxide in a CdS precursor solution using a microwave synthesis system. The photocatalytic performances of CdS-RGO composites in the reduction of Cr(VI) are investigated. The results show that CdS-RGO composites exhibit enhanced photocatalytic performance for the reduction of Cr(VI) with a maximum removal rate of 92% under visible light irradiation as compared with pure CdS (79%) due to the increased light absorption intensity and the reduction of electron-hole pair recombination in CdS with the introduction of RGO.
Publisher: AIP Publishing
Date: 15-10-2012
DOI: 10.1063/1.4759207
Abstract: We have formulated the size and temperature dependence of the phonon relaxation dynamics for CdS, CdSe, Bi2Se3, and Sb2Te3 nanostructures based on the framework of bond order–length–strength correlation, core-shell configuration, and local bond averaging approach. The Raman shifts are correlated directly to the identities (nature, order, length, and energy) of the representative bond of the specimen without needing involvement of the Grüneisen mode parameters or considering the processes of phonon decay or multi-phonon resonant scattering. Quantitative information of the Debye temperature, the atomic cohesive energy, the reference frequencies from which the Raman shifts proceed, and the effective coordination numbers of the randomly sized particles, as well as the length and energy of the representative bond, has been obtained. It is clarified that the size-induced phonon softening arises intrinsically from the cohesive weakening of the undercoordinated atoms in the skin up to three atomic layers and the thermally derived phonon softening results from the thermally lengthening and weakening of bonds. Developed approach empowers the Raman technique in deriving quantitative and direct information regarding bond stiffness relaxation with applied stimuli such as coordination, mechanical, thermal, and chemical environment, which are crucial to practical applications.
Publisher: Springer Science and Business Media LLC
Date: 21-10-2013
DOI: 10.1038/SREP03005
Abstract: The structural symmetry and molecular separation in water and ice remain uncertain. We present herewith a solution to unifying the density, the structure order and symmetry, the size (H-O length d H ) and the separation (d OO = d L + d H or the O:H length d L ) of molecules packing in water and ice in terms of statistic mean. This solution reconciles: i) the d L and the d H symmetrization of the O:H-O bond in compressed ice, ii) the d OO relaxation of cooling water and ice and, iii) the d OO expansion of a dimer and between molecules at water surface. With any one of the d OO , the density ρ(g·cm −3 ), the d L and the d H , as a known input, one can resolve the rest quantities using this solution that is probing conditions or methods independent. We clarified that: i) liquid water prefers statistically the mono-phase of tetrahedrally-coordinated structure with fluctuation, ii) the low-density phase (supersolid phase as it is strongly polarized with even lower density) exists only in regions consisting molecules with fewer than four neighbors and, iii) repulsion between electron pairs on adjacent oxygen atoms dictates the cooperative relaxation of the segmented O:H-O bond, which is responsible for the performance of water and ice.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA00112A
Abstract: Mo(100, 110) skins and atomic clusters share the common nature of atomic undercoordination induced local bond strain and the associated quantum entrapment and valence electron polarization.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Springer Singapore
Date: 2014
Publisher: Elsevier BV
Date: 06-1997
Publisher: American Chemical Society (ACS)
Date: 24-06-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 08-10-2014
DOI: 10.1039/C4CP04080E
Abstract: Infrared spectroscopy and contact-angle measurements revealed that NaCl salting has the same effect as heating on O:H phonon softening and H-O phonon stiffening, but has the opposite effect on skin polarization of liquid water. The mechanics of thermal modulation of O-O Coulomb repulsion [Sun, et al., J. Phys. Chem. Lett., 2013, 4, 3238] may suggest a possible mechanism for this NaCl involved Hofmeister effect, aqueous solution modulated surface tension and its abilities in protein dissolution, from the perspective of Coulomb mediation of interaction within the O:H-O bond.
Publisher: Elsevier BV
Date: 2006
Publisher: Elsevier BV
Date: 04-2011
Publisher: Public Library of Science (PLoS)
Date: 07-04-2016
Publisher: Trans Tech Publications, Ltd.
Date: 07-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.444.17
Abstract: Shrinking the size of a solid down to nanometer scale is indeed fascinating, which makes all the otherwise constant physical quantities to be tunable such as the Young’s modulus, dielectric constant, melting point, etc. The variation of size also generates novel properties that can hardly be seen in the bulk such as the conductor-insulator and nonmagnetic-magnetic transition of noble metals at the nanoscale. Although the physics of materials at the nanoscale has been extensively investigated, the laws governing the energetic and dynamic behavior of electrons at such a scale and their consequences on the tunable physical properties of nanostructures have not been well understood [C. Q. Sun, Prog Solid State Chem 35, 1-159 (2007) Prog Mater Sci 54, 179-307 (2009)]. The objective of the contribution is to update the recent progress in dealing with the coordination-resolved energetic and dynamic behavior of bonds in the low-dimensional systems with consideration of the joint effect of temperature and pressure. It is shown that the broken-bond-induced local strain and the associated charge and energy quantum trapping at the defect sites perturbs the atomic cohesive energy, electroaffinity, the Hamiltonian and the associated properties of entities ranging from point defects, surfaces, nanocavities and nanostructures. Application of the theories to observations has led to consistent understanding of the behavior of nanometer-sized materials and the interdependence of these entities as well as the means of determining the bond energy through the temperature-dependent measurements.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Springer Singapore
Date: 2016
Publisher: Elsevier BV
Date: 2005
Publisher: Desalination Publications
Date: 2012
Publisher: Elsevier BV
Date: 04-2018
Publisher: World Scientific Pub Co Pte Lt
Date: 12-2003
DOI: 10.1142/S0218625X03005724
Abstract: Crystal binding energy of a core electron at the 3d 5/2 level of a Pd atom has been estimated to be -4.0±0.02 eV by decoding the X-ray photoelectron spectra obtained from both the Pd surfaces and the Pd nanoparticles. Findings indicate that the increase in the binding energy originates from the effect of coordination number (CN) imperfection of atoms at a flat surface or at the curved surface of a nanosolid. The CN imperfection shortens the remaining bonds of the lower-coordinated atoms spontaneously associated with bond energy increase, which perturbs the Hamiltonian of an extended solid and hence shifts the core level to higher binding energy. Therefore, the significance of atomic CN imperfection cannot be overlooked in dealing with a low-dimensional system, and the recent bond-order–length–strength (BOLS) correlation mechanism is essentially adequate, for the significance of atomic CN imperfection.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2RA00512C
Publisher: AIP Publishing
Date: 06-02-2012
DOI: 10.1063/1.3685777
Abstract: By means of the nonequilibrium Green's functions and the density functional theory, we have investigated the electronic transport properties of C60 based electronic device with different intermolecular interactions. It is found that the electronic transport properties vary with the types of the interaction between two C60 molecules. A fast electrical switching behavior based on negative differential resistance has been found when two molecules are coupled by the weak π − π interaction. Compared to the solid bonding, the weak interaction is found to induce resonant tunneling, which is responsible for the fast response to the applied electric field and hence the velocity of switching.
Publisher: AIP Publishing
Date: 15-10-2007
DOI: 10.1063/1.2798941
Abstract: The thermally induced softening of the elastic and vibronic identities in crystals and their correlations have long been a puzzle. Analytical solutions have been developed, showing that the detectable elastic and vibronic properties could be related directly to the bonding parameters, such as bond length and strength, and their response to the temperature change. Reproduction of measured T-dependent Young’s modulus and Raman shift of Si, Ge, and diamond reveals that the thermally driven softening of the elasticity and the optical Raman frequency arises from bond expansion and vibration, with derived information about the atomic cohesive energy and clarification of their interdependence.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CP05729A
Abstract: A coordination environment resolves the electron binding-energy shift of Rb and Cs clusters.
Publisher: Springer Singapore
Date: 2014
Publisher: American Chemical Society (ACS)
Date: 18-12-2002
DOI: 10.1021/JP027027K
Publisher: World Scientific Pub Co Pte Lt
Date: 10-2011
DOI: 10.1142/S2010135X11000549
Abstract: Correlation between the elastic and the vibronic behavior of TiO 2 and their responses to the variation of crystal size, applied pressure, and measuring temperature has been investigated based on the bond order–length-strength correlation mechanism. Theoretical reproduction of the measurements clarified that: (i) the elastic modulus (B) and the Raman shifts (Δω) are strongly correlated and we can know either one of the B or the Δω from the other (ii) the under-coordination induced cohesive energy loss and the energy density gain in the surface up to skin depth determines the size effect (iii) bond expansion and bond weakening due to thermal vibration originates the thermally softened elastic modulus and the Raman shifts and (iv) bond compression and bond strengthening results in the mechanically stiffened elastic modulus and the Raman shifts. With the developed premise, one can predict the changing trends of the concerned properties with derivatives of quantitative information of the atomic cohesive energy, binding energy density, Debye temperature, and nonlinear compressibility of the specimen.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CP23937J
Abstract: By applying the nonequilibrium Green's functions and the density-functional theory, we investigate the electronic structures and transport properties of fluorinated zigzag-edged boron nitride nanoribbons. The results show that the transition between half-metal and semiconductor in zigzag-edged boron nitride nanoribbons can be realized by fluorination at different sites or by the change of the fluorination level. Moreover, the negative differential resistance and varistor-type behaviors can also be observed in such fluorinated zigzag-edged boron nitride nanoribbon devices. Therefore, the fluorination of zigzag-edged boron nitride nanoribbons will provide the possibilities for a multifunctional molecular device design.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Springer Science and Business Media LLC
Date: 07-04-2016
DOI: 10.1038/SREP24140
Abstract: Two-dimensional crystals stacked by van der Waals coupling, such as twisted graphene and coupled graphene-BN layers with unusual phenomena have been a focus of research recently. As a typical representative, with the modulation of structural symmetry, stacking orders and spin-orbit coupling, transitional metal dichalcogenides have shown a lot of fascinating properties. Here we reveal the effect of stacking orders with spin-orbit coupling on the electronic properties of few-layer 3R-type MoS 2 by first principles methods. We analyze the splitting of states at the top of valence band and the bottom of conduction band, following the change of stacking order. We find that regardless of stacking orders and layers’ number, the spin-up and spin-down channels are evidently separated and can be as a basis for the valley dependent spin polarization. With a model Hamiltonian about the layer’s coupling, the band splitting can be effectively analyzed by the coupling parameters. It is found that the stacking sequences, such as abc and abca, have the stronger nearest-neighbor coupling which imply the popular of periodic abc stacking sequence in natural growth of MoS 2 .
Publisher: American Chemical Society (ACS)
Date: 03-10-2011
DOI: 10.1021/JP207237D
Publisher: American Chemical Society (ACS)
Date: 12-01-2010
DOI: 10.1021/JP909259S
Publisher: World Scientific Pub Co Pte Lt
Date: 04-1999
DOI: 10.1142/S0218625X99000196
Abstract: A new model is presented to describe the quantum confinement and surface passivation effects of nanoclusters. The quantum well depth (ϕ) and the band gap width (E g ) of nanoclusters are independent concepts, because the ϕ depends on the surface electron density while the E g is a function of the crystal field of the solid. The ϕ and E g can be correlated with the joint physical and chemical effects, which are quite simple but have rarely been noticed. It is suggested that the bond contraction at the surface and the rise in the surface-to-volume ratio (γ), as well as the cluster interaction, enhance intrinsically the crystal field and hence the band gap E g . Reaction with electronegative elements, such as oxygen and nitrogen, widens extrinsically the E g by producing holes below the Fermi level [Appl. Phys. Lett.72, 1706 (1998)]. The formulation agrees well with experimental observations on the band gap enlargement by reducing particle size.
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: World Scientific Pub Co Pte Lt
Date: 30-10-1997
DOI: 10.1142/S0217984997001328
Abstract: Spectroscopy covering energies around Fermi level of a metal is of particular interest as it does give direct information of bond forming and its consequence on the energy states (DOS). However, the origin of some outstanding spectral features from metal surface with chemisorbed oxygen has not yet been well established. It is shown in this letter that a bond-to-band model for oxidation enables the nature of a sum of spectral features to be consistently defined. All the spectral changes in the STS, XPS, UPS, photoemission spectroscopy (PES) and the thermal desorption spectroscopy (TDS) are classified by four DOS features around Fermi level and three bonding processes. Such a definition leads not only to new knowledge of the nature of O-metal interaction but also to a direct understanding of the bond-and-band forming dynamics.
Publisher: Springer Singapore
Date: 2014
Publisher: Elsevier BV
Date: 03-2018
Publisher: American Chemical Society (ACS)
Date: 10-2004
DOI: 10.1021/JP0465276
Publisher: Elsevier BV
Date: 05-1997
Publisher: IOP Publishing
Date: 15-01-2009
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 02-1998
Publisher: World Scientific Pub Co Pte Lt
Date: 20-01-2002
DOI: 10.1142/S0217979202009718
Abstract: The interfacial characteristics of the TiSi 2 / Si structure were investigated in detail. It was found that the semi-coherent formed with a certain disregistry which was periodically taken up by the misfit dislocations between every three (030) C49 planes. The semi-coherent interface dominated the interfacial structure in the material and was responsible to the wavy surface of TiSi 2 / Si structure. However, the interface accommodated higher energy was a favorable nucleation sites for the C54 phase. Its existence may enhance the C54 phase formation in the further thermal treatments.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA03205A
Abstract: Atomic undercoordination shortens the interatomic bond, deepens the energy level, raises the local energy density and lowers the atomic cohesive energy of Na solid skins and clusters.
Publisher: AIP Publishing
Date: 15-08-2011
DOI: 10.1063/1.3626044
Abstract: Correlation between the elastic modulus (B) and the Raman shift (Δω) of TiO2 and their responses to the variation of crystal size, applied pressure, and measuring temperature have been established as a function depending on the order, length, and energy of a representative bond for the entire specimen. In addition to the derived fundamental information of the atomic cohesive energy, binding energy density, Debye temperature and nonlinear compressibility, theoretical reproduction of the observations clarified that (i) the size effect arises from the under-coordination induced cohesive energy loss and the energy density gain in the surface up to skin depth (ii) the thermally softened B and Δω results from bond expansion and bond weakening due to vibration and, (iii) the mechanically stiffened B and Δω results from bond compression and bond strengthening due to mechanical work hardening. With the developed premise, one can predict the changing trends of the concerned properties with derivatives of quantitative information as such from any single measurement alone.
Publisher: Elsevier BV
Date: 06-2007
Publisher: Wiley
Date: 22-06-2007
Publisher: AIP Publishing
Date: 17-10-2011
DOI: 10.1063/1.3656704
Abstract: From the perspective of bond order-length-strength correlation and the local bond averaging approach, we have formulated the number-of-layer resolved Raman shifts of graphene, with quantification of the referential origins from which the Raman shifts proceed and clarification of their origins. It is found that the primary D mode and the secondary 2D mode are dominated by the interaction between a specific atom and its nearest neighbors while the G mode by the dimer interaction, and therefore red shift happens to the D/2D phonons and blue shift to the G mode upon the number-of-layer is reduced.
Publisher: Elsevier BV
Date: 02-2012
Publisher: Springer Science and Business Media LLC
Date: 11-08-2012
Publisher: AIP Publishing
Date: 16-11-2015
DOI: 10.1063/1.4935604
Abstract: Strain-induced graphene phonon softening and phonon band splitting are indeed fascinating, which were attributed to the phonon double resonant scattering without intrinsic involvement of C-C bond relaxation. Here, we show that the lengthening and weakening of the C-C bond softens the phonon and that the mismatching between the uniaxial strain and the C3v bond geometry splits the band. In addition to the force constant of 11.8 N/m for a C-C bond in graphene, consistency between theory and measurements derives that if the strain is along a bond, maximal band splitting happens if the strain is perpendicular, no band splitting occurs.
Publisher: World Scientific Pub Co Pte Lt
Date: 10-03-2000
DOI: 10.1142/S0217984900000318
Abstract: A new description of bonding and band-forming is presented for the nature and dynamics of O–Rh(111) and O–Ru(0001) surface bonding and its consequences on the behavior of atoms and electrons at the surfaces. The sp-orbital hybridization and electron transportation define that oxygen retains inside the hcp hollow site throughout the course of reaction in which O -1 forms and then O -2 -hybrid follows with production of nonbonding lone pairs and the lone-pair induced antibonding dipoles. Consequently, the valence band and surface morphology are modified with the corresponding features, and the radial and pairing-row reconstruction arises in the corresponding phases.
Publisher: Elsevier BV
Date: 02-2011
Publisher: Elsevier BV
Date: 11-2012
Publisher: IOP Publishing
Date: 12-2008
Publisher: Trans Tech Publications, Ltd.
Date: 12-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.602-604.2065
Abstract: Maximum normal stress criterion can be used to determine the cracking angle in the uniform and non-uniform zone. According to this theory, the propagating process of the crack in non-uniform composite material is simulated based on the finite element method. The results show that the crack advances wave-like and basically along the direction perpendicular to the maximum normal stress, which is of great guiding significance for the fracture resistance of such kind of structure.
Publisher: Elsevier BV
Date: 02-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CY00622H
Abstract: Light-conversion phosphor-based composites including up-conversion, down-conversion, and long afterglow phosphor-semiconductors for efficient photocatalysis are summarized.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2NR11154C
Abstract: Although the dielectric behavior of nanostructured semiconductors has been intensively investigated, the physics behind observations remains disputed with possible mechanisms such as quantum confinement and dangling bond polarization. Here we show that theoretical reproduction of the measured dielectric suppression of Ge nanocrystals asserts that the dielectric suppression originates from the shorter and stronger bonds at the skin-deep surface, the associated local densification and quantum entrapment of energy. Coordination-imperfection induced local quantum entrapment perturbs the Hamiltonian that determines the band gap and hence, the process of electron polarization consequently.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CP21421G
Abstract: We report an efficient yet simple technology of photoelectron spectroscopic purification for identifying the capability of, and direction of charge flow in, a catalyst in a reaction, which has enabled the finding, for the first time, of the similarity of the valence band of tungsten edges to that of Rh adatoms and Ag/Pd alloy and hence suggested that W undercoordinated atoms could be a suitable candidate for replacing the costly Rh adatoms and Ag/Pd alloy as a cheaper, richer, and efficient donor-type catalyst for CO and NO oxidation applications. The new technology and new findings will be stimulating to the community for new catalyst design and identification and provide a better understanding of the electronic process of a catalytic reaction associated with undercoordinated atoms.
Publisher: World Scientific Pub Co Pte Lt
Date: 02-1999
DOI: 10.1142/S0218625X99000135
Abstract: It is shown that the atomic states, bonding dynamics, driving force and bond strain for the C–Ni(100) surface reaction can be consistently understood by considering the sp orbital hybridization of carbon. It is proposed that, at the initial stage, C sinks into the hollow site and bonds to one Ni atom underneath. The C -1 polarizes and pushes its surface neighbors radially away from the site center, and hence a Ni 5 C cluster forms. Then, sp hybridization of the C happens, leading to a Ni 4 C tetrahedron. Besides the Ni + underneath the C adsorbate, three of the four surface Ni neighbors donate electrons to the adsorbate. The half-monolayer coverage of C defines therefore half of the surface Ni atoms to be Ni + ions and the other half to be Ni 2+ ions. As a result, one-dimensional nonuniform "- (+) - (2+) – (2+) - (+) – (+) -" chains form along the 11 direction. It is suggested that the forces arising from charge redistribution drive the reconstruction. Calculation reveals that an increase of ~ 90 dyne electrostatic repulsion along the 11 direction and a responding ~ 130 dyne bond compression stabilize the network of (2× 2)p4g clock rotation.
Publisher: WORLD SCIENTIFIC
Date: 12-2008
Publisher: Trans Tech Publications, Ltd.
Date: 02-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.472-475.1267
Abstract: In this paper, J-integral of inhomogeneous welded joint is calculated by use of the combination of finite element method and virtual crack extension method, and the impact of strength matching on J-integral is studied as well. The analysis results show that the strength matching factor affects J-integral value greatly, that is, low matching of inhomogeneous welded joint of same steel can help to improve the ductility of the welded joint and the influence of the matching performance of dissimilar steel welded joint is more complex.
Publisher: Elsevier BV
Date: 09-2016
Publisher: Trans Tech Publications, Ltd.
Date: 09-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.447-448.734
Abstract: In this paper, three types of titanium dioxide structures (anatase, heated amorphous and amorphous) from peroxo titanium complex were deposited on glass and wafer substrates by spraying technique. Influences of crystal structure, morphology and sodium ion on UV induced hydrophilicity were studied. X-ray diffraction revealed that crystalline anatase coatings are extremely hydrophilic ( °) under UV irradiation (indoor) while the amorphous coatings are still hydrophobic on both glass and wafer substrate with contact angles as high as 70º. When amorphous coating was heated at 450°C, its structure was converted into crystalline anatase, and hence its UV induced hydrophilicity behavior on wafer substrate became similar to that of anatase. However, this UV induced hydrophilicity was inhibited on heated glass (450°C), suggesting that sodium ions in the glass might be responsible for the differences between silicon wafer and glass. With increasing coating thickness, such inhibition effect was reduced, but the hydrophilicity still could not reach the level of anatase. After 6 months of outdoor exposure, water contact angle for amorphous, heated amorphous and anatase were 61°, 26.6° and 12.1°, respectively. Also, X-ray diffraction suggested that amorphous is not converted into anatase after long period of UV exposure, although coating morphologies are changed based on Scanning Electron Microscopic observation. It is concluded that the crystal structure, coating morphology and sodium ion concentration have key impact on the photocatalytic properties on glass substrate.
Publisher: Wiley
Date: 08-01-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP01783E
Abstract: We examined the effects of atomic hetero- and under-coordination on the relaxation of the interatomic bonding and electronic binding energy of Li and LiNa cluster alloying using a combination of the bond-order-length-strength correlation and density functional theory calculations.
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5RA24265G
Abstract: A combination of DFT and UPS studies revealed that N chemisorption modified DOS for Ti(0001) surface with four features: bonding, nonbonding, holes, and dipoles. These states associated with optical, electrical, and mechanical properties of nitrides.
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Springer Singapore
Date: 2014
Publisher: Elsevier BV
Date: 08-2016
Publisher: Springer Singapore
Date: 2014
Publisher: Wiley
Date: 07-2016
DOI: 10.1002/JRS.4964
Publisher: Wiley
Date: 14-06-2016
DOI: 10.1002/JRS.4963
Publisher: Springer Singapore
Date: 2014
Publisher: AIP Publishing
Date: 15-01-2010
DOI: 10.1063/1.3291103
Abstract: The band gap and optical properties (dielectric functions and optical constants) of Ge thin films with various thicknesses below 50 nm, which were synthesized with electron beam evaporation technique, have been determined using spectroscopic ellipsometry and UV-visible spectrophotometry. The optical properties are well described with the Forouhi–Bloomer model. Both the band gap and optical properties show a strong dependence on the film thickness. For film thickness smaller than ∼10 nm, a band gap expansion is observed as compared to bulk crystalline Ge, which is attributed to the one-dimensional quantum confinement effect. However, a band gap reduction was observed for thickness larger than ∼10 nm, which is explained in terms of the amorphous effect in the Ge layers.
Publisher: Elsevier BV
Date: 2018
Publisher: SPIE
Date: 09-09-2014
DOI: 10.1117/12.2059745
Publisher: Elsevier BV
Date: 2015
Publisher: World Scientific Pub Co Pte Lt
Date: 10-1998
DOI: 10.1142/S0218625X98001389
Abstract: It is shown that the model for oxygen chemisorption improves our understanding of the [Formula: see text] surface reaction. The disordered p (2×1)-O precursor is identified as molecule adsorption in which the paired O -1 rests on top of the surface along the close-packed direction. Meanwhile, O -1 polarizes its rest neighbors, leading to the protruding domain boundaries. At higher coverage, c (2×4)-4O and then p (2×1)-2O develop due to O -2 hybridization. O -2 is located at a threefold hollow site and forms a tetrahedron with two Co atoms at the surface and one atom in the second layer. The lack of one atom of bonding is compensated for by an electron cloud of dipoles namely, a virtual bond forms. The virtual bonding lowers the STM protrusions and narrows the antibonding band.
Publisher: Elsevier BV
Date: 2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0EE00434K
Publisher: IOP Publishing
Date: 07-06-2005
Publisher: Springer Singapore
Date: 2014
Publisher: American Vacuum Society
Date: 03-2005
DOI: 10.1116/1.1868692
Abstract: Field emission properties of carbon nanotubes under mechanical stress have been investigated. The emission threshold fields initially decrease from 2.3to0.6V∕μm before rising back to 3.1V∕μm with increasing mechanical stress applied externally to the film. This behavior from nanotube composites has not been reported and is believed to be associated with modification to the work function of the nanotubes. This work suggests a possible application for these composite films as electromechanical high power switches.
Publisher: Springer Science and Business Media LLC
Date: 12-1999
Publisher: Wiley
Date: 11-04-2007
DOI: 10.1002/JRS.1683
Publisher: Elsevier BV
Date: 11-2017
Publisher: AIP Publishing
Date: 30-03-2009
DOI: 10.1063/1.3109786
Abstract: It has long been puzzling regarding the trends and physical origins of the size-effect on the elasticity of ZnO nanostructures. An extension of the atomic “coordination-radius” correlation premise of Pauling and Goldschmidt to energy domain has enabled us to clarify that the elastic modulus is intrinsically proportional to the sum of bond energy per unit volume and that the size-induced elastic stiffening arises from (i) the broken-bond-induced local strain and skin-depth energy pinning and (ii) the tunable fraction of bonds between the undercoordinated atoms, and therefore, the elastic modulus of ZnO nanostructures should increase with the inverse of feature size.
Publisher: American Chemical Society (ACS)
Date: 21-10-2013
DOI: 10.1021/JP407836N
Abstract: A combination of the Lagrangian mechanics of oscillators vibration, molecular dynamics decomposition of volume evolution, and Raman spectroscopy of phonon relaxation has enabled us to resolve the asymmetric, local, and short-range potentials pertaining to the hydrogen bond (O:H-O) in compressed ice. Results show that both oxygen atoms in the O:H-O bond shift initially outwardly with respect to the coordination origin (H), lengthening the O-O distance by 0.0136 nm from 0.2597 to 0.2733 nm by Coulomb repulsion between electron pairs on adjacent oxygen atoms. Both oxygen atoms then move toward right along the O:H-O bond by different amounts upon being compressed, approaching identical length of 0.11 nm. The van der Waals potential VL(r) for the O:H noncovalent bond reaches a valley at -0.25 eV, and the lowest exchange VH(r) for the H-O polar-covalent bond is valued at -3.97 eV.
Publisher: American Chemical Society (ACS)
Date: 25-04-2019
DOI: 10.1021/ACS.JPCLETT.9B01047
Abstract: Pentazole anion, the best candidate for full-nitrogen energetic materials, can be isolated only from acidic solution for unclear reasons, which hinders the high-yield realization of a full-nitrogen substance with higher energy density. Herein, we report for the first time the discovery of the dual aromaticity (π and σ) of cyclo-N
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0NR00273A
Abstract: An edge-modified tight-binding (TB) approximation has been developed, enabling us to clarify the energetic origin of the width-dependent band gap (E(G)) expansion of the armchaired and the reconstructed zigzag-edged graphene nanoribbons with and without hydrogen termination. Consistency between the TB and the density-function theory calculations affirmed that: (i) the E(G) expansion originates from the Hamiltonian perturbation due to the shorter and stronger bonds between undercoordinated atoms, (ii) the combination of the edge-to-width ratio with a local bond strain up to 30% and the associated 152% potential well depression determines the width dependent E(G) change and, (iii) hydrogen termination affects insignificantly the band gap width as the H-passivation minimizes the midgap impurity states.
Publisher: Trans Tech Publications, Ltd.
Date: 10-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.684.64
Abstract: The finite element method combined with the singular element was adopted to study the effects of thickness ratio of the coating-matrix, elastic modulus ratio of the coating-matrix, and the ratio of ensile stress and shear stress on the coating top on the stress intensity of the interface crack on the coating-matrix. Through calculations, results show that elastic modulus ratio of the coating-matrix has little effect on stress intensity factor of interface crack, while the thickness ratio and the tensile stress and shear stress ratio on the coating top have a great effect on it, which should be controlled in the coating-matrix structure design.
Publisher: American Chemical Society (ACS)
Date: 25-01-2008
DOI: 10.1021/JP077719E
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C1NR11280E
Abstract: From the perspective of bond relaxation and bond vibration, we have formulated the Raman phonon relaxation of graphene, under the stimuli of the number-of-layers, the uni-axial strain, the pressure, and the temperature, in terms of the response of the length and strength of the representative bond of the entire specimen to the applied stimuli. Theoretical unification of the measurements clarifies that: (i) the opposite trends of the Raman shifts, which are due to the number-of-layers reduction, of the G-peak shift and arises from the vibration of a pair of atoms, while the D- and the 2D-peak shifts involve the z-neighbor of a specific atom (ii) the tensile strain-induced phonon softening and phonon-band splitting arise from the asymmetric response of the C(3v) bond geometry to the C(2v) uni-axial bond elongation (iii) the thermal softening of the phonons originates from bond expansion and weakening and (iv) the pressure stiffening of the phonons results from bond compression and work hardening. Reproduction of the measurements has led to quantitative information about the referential frequencies from which the Raman frequencies shift as well as the length, energy, force constant, Debye temperature, compressibility and elastic modulus of the C-C bond in graphene, which is of instrumental importance in the understanding of the unusual behavior of graphene.
Publisher: Elsevier BV
Date: 06-1997
Publisher: American Chemical Society (ACS)
Date: 17-01-2012
DOI: 10.1021/JP2092576
Publisher: Elsevier BV
Date: 03-1999
Publisher: IOP Publishing
Date: 26-01-2000
Publisher: Elsevier BV
Date: 12-2003
Publisher: Elsevier BV
Date: 06-2005
Publisher: AIP Publishing
Date: 26-07-2004
DOI: 10.1063/1.1766086
Abstract: CF 4 plasma-passivation enhanced size dependence of the blueshift in photoemission and photoabsorption, E2p-level shift, and band-gap expansion of porous silicon has been measured and analyzed numerically based on the recent “bond order-length-strength” correlation [C. Q. Sun, Phys. Rev. B 69, 045105 (2004)]. Matching predictions to the measurements conducted before and after fluorination reveals that fluorination further enhances both the crystal binding intensity that determines the band gap and core level shift and the electron-phonon coupling that contributes to the energies of photoemission and photoabsorption. This approach enables us to discriminate the effect of surface-bond contraction from the effect of surface-bond nature alteration on the unusual behavior of photons, phonons, and electrons in nanosolid Si.
Publisher: American Physical Society (APS)
Date: 19-10-2006
Publisher: American Chemical Society (ACS)
Date: 06-07-2009
DOI: 10.1021/JP904445A
Publisher: Elsevier BV
Date: 06-2009
Publisher: American Chemical Society (ACS)
Date: 19-02-2004
DOI: 10.1021/JP037891S
Publisher: Elsevier BV
Date: 09-2019
Publisher: Wiley
Date: 26-11-2015
Abstract: Although germanium performs amazingly well at sites surrounding hetero-coordinated impurities and under-coordinated defects or skins with unusual properties, having important impact on electronic and optical devices, understanding the behavior of the local bonds and electrons at such sites remains a great challenge. Here we show that a combination of density functional theory calculations, zone-resolved X-ray photoelectron spectroscopy, and bond order length strength correlation mechanism has enabled us to clarify the physical origin of the Ge 3d core-level shift for the under-coordinated (111) and (100) skin with and without hetero-coordinated H2 , O2 , H2 O, H2 O2 , HF impurities. The Ge 3d level shifts from 27.579 (for an isolated atom) by 1.381 to 28.960 eV upon bulk formation. Atomic under-coordination shifts the binding energy further to 29.823 eV for the (001) and to 29.713 eV for the (111) monolayer skin. Addition of O2 , HF, H2 O, H2 O2 and Au impurities results in quantum entrapment by different amounts, but H adsorption leads to polarization.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B919982A
Abstract: Lattice strain plays a crucial role on the properties of nanoparticles. Although the effect of lattice strain on nanoparticles has been widely studied in experimental measurements and calculations, its physical mechanism from the perfective of bond identities is still poorly understood. Herein we put forward an analytical solution of the size effect and external stimuli such as pressure and temperature dependence of lattice strain and bulk modulus of a nanoparticle from the perspective of atomistic origin. A shell-core configuration has been considered for the nanoparticle structure. It has been found that the lattice strain as well as quantum trapping and energy storage exerted by the compressive stress and thermal stress would be responsible for the mechanical behavior of nanoparticles. The theoretical predictions were well consistent with the experimental data and ab initio calculations, implying that the model could be expected to be a general approach to understand mechanical behavior in nanomaterials.
Publisher: Elsevier BV
Date: 11-2007
DOI: 10.1016/J.JCIS.2007.06.055
Abstract: We used the Langmuir-Blodgett (LB) technique to construct a well-defined and structure-controllable photochromic material-a highly ordered multilayer film composed of dioctadecylamine and 12-molybdophosphoric acid (PMo12). We identified well-ordered lamellar structures using X-ray diffraction, polarized IR, and Raman spectra, and we determined a packing model of the two components in the LB film. We found the Keggin structure and fundamental features of the PMo12 ion to be maintained in the hybrid film. This hybrid LB film displayed photochromic properties upon UV light irradiation and we observed the following process from first-order kinetics. The photochromism exhibited the ability to switch between colorless and blue. A fading process occurred when the film was exposed to ambient air or O2 in the dark. During the color change, the packing structure of the film was well maintained. We also examined the electrochemical behavior of the hybrid LB film by cyclic voltammetry in detail and we propose different kinetic mechanisms for the film before and after irradiation.
Publisher: Springer Science and Business Media LLC
Date: 20-11-2009
Publisher: American Chemical Society (ACS)
Date: 20-12-2019
DOI: 10.26434/CHEMRXIV.11369382.V1
Abstract: The combination of intermolecular hydrogen bond (X:H–Y) tension and the anti-HB (H↔H) or super-HB (X⇔Y) compression not only stabilizes the structure but also stores energy by shortening the intramolecular covalent bonds. The X:H tension constrains and the X⇔Y compression fosters explosion.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP02499K
Abstract: Atomic under-coordination fascinated catalytic and magnetic properties of Pt and Rh nanoclusters have been studied by DFT calculations, and consistency with the calculation and experimental results confirmed predications based on BOLS correlation.
Publisher: Springer Science and Business Media LLC
Date: 12-2015
DOI: 10.1007/S40544-015-0097-Z
Abstract: Superlubricity means non-sticky and frictionless when two bodies are set contacting motion. Although this occurrence has been extensively investigated since 1859 when Faraday firstly proposed a quasiliquid skin on ice, the mechanism behind the superlubricity remains uncertain. This report features a consistent understanding of the superlubricity pertaining to the slipperiness of ice, self-lubrication of dry solids, and aqueous lubricancy from the perspective of skin bond-electron-phonon adaptive relaxation. The presence of nonbonding electron polarization, atomic or molecular undercoordination, and solute ionic electrification of the hydrogen bond as an addition, ensures the superlubricity. Nonbond vibration creates soft phonons of high magnitude and low frequency with extraordinary adaptivity and recoverability of deformation. Molecular undercoordination shortens the covalent bond with local charge densification, which in turn polarizes the nonbonding electrons making them localized dipoles. The locally pinned dipoles provide force opposing contact, mimicking magnetic levitation and hovercraft. O:H−O bond electrification by aqueous ions has the same effect of molecular undercoordination but it is throughout the entire body of the lubricant. Such a Coulomb repulsivity due to the negatively charged skins and elastic adaptivity due to soft nonbonding phonons of one of the contacting objects not only lowers the effective contacting force but also prevents charge from being transited between the counterparts of the contact. Consistency between theory predictions and observations evidences the validity of the proposal of interface elastic Coulomb repulsion that serves as the rule for the superlubricity of ice, wet and dry frictions, which also reconciles the superhydrophobicity, superlubricity, and supersolidity at contacts.
Publisher: World Scientific Pub Co Pte Lt
Date: 20-01-2002
DOI: 10.1142/S0217979202009731
Abstract: Grain growth dependence of microstructure in La 2/3 Ba 1/3 MnO 3+δ oxides has been studied in detail. The result shows that the crystals grew along three vertical axes with a concentric terrace pattern in the s le sintered at 1673K while the oxides sintered at 1573K grew with a lateral growth manner. However, the concentric terrace growth pattern resulted in twin microstructure in the cooling processing and the lateral growth manner produced non-twin microstrcuture in the oxides at ambient, respectively. It was found that the oxide with twin microstructure has a much higher saturation magnetization than the non-twin oxide. This may be due to the easier alignment of the domains in the twin-grained oxide through the rearrangement of dislocations in twin-boundaries.
Publisher: American Chemical Society (ACS)
Date: 25-10-2018
DOI: 10.26434/CHEMRXIV.7246946.V1
Abstract: A combination of the temporally- and spatially-resolved phonon spectroscopy has enabled calibration of hydrogen bond transition from the vibration mode of heavy water to the core-shelled nanodroplet and the sub-nanosized ionic hydration shell in terms of phonon abundance-lifetime-stiffness. It is uncovered that charge injection by salt solvation and skin formation by molecular undercoordination (often called confinement) share the same supersolidity of H–O (D–O as a probe) bond contraction, O:H elongation, and electron polarization. The bond transition stems the solution viscosity, surface stress, and slows down the molecular dynamics. The skin reflection further hinders phonon energy dissipation and thus lengthens the phonon lifetime of the nanodroplet.
Publisher: American Chemical Society (ACS)
Date: 07-11-2002
DOI: 10.1021/JP026814E
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4TC00670D
Abstract: Lead (Pb) demonstrates pronounced energy states pertaining to undercoordinated skin and edge atoms.
Publisher: Elsevier BV
Date: 2003
Publisher: American Chemical Society (ACS)
Date: 28-03-2011
DOI: 10.1021/JP110613P
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CP06115G
Abstract: Electrostatic polarization or molecular undercoordination endows the supersolidity by shortening and stiffening the H–O bond and lengthening and softening the O:H nonbond, deepening the O 1s energy level, and prolonging the photoelectron and phonon lifetime. The supersolid phase is less dense, viscoelastic, mechanically and thermally more stable, which offsets boundaries of structural phases and critical temperatures for phase transition of the coordination-resolved core–shell structured ice such as the ‘no man's land’ supercooling and superheating.
Publisher: AIP Publishing
Date: 15-06-2009
DOI: 10.1063/1.3156811
Abstract: The Hg2CuTi-type structure is found to be preferable energy wise than the Cu2MnAl-type structure for full-Heusler Cr2MnAl and exhibits half-metallic ferromagnetism based on first principles. The calculations for the mixed compounds with disorder between B and D sublattices reveal that the case of exchanging one atom maintains the half-metallicity while the case of exchanging two atoms loses it. The electronic structures of the atoms at sites A or C are affected mainly by the nearest-neighboring coordination while that of the atoms at site B are determined by the next-nearest-neighboring coordination.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2RA01107G
Publisher: Elsevier BV
Date: 07-2008
Publisher: American Chemical Society (ACS)
Date: 02-07-2018
Abstract: From the perspective of O:H-O bond cooperativity, we analyzed the solute capability of transiting the O:H-O bond from the mode of ordinary water to the hydration state and its consequence on the solution viscosity and surface stress. Phonon spectrometric results suggest that glycine and its N-methyl derivatives strongly affect the surrounding solvent molecules through H ↔ H repulsion and dipolar polarization. The H ↔ H interproton repulsion disrupts the surface stress, and the polarization enhances the solution viscosity.
Publisher: Springer International Publishing
Date: 2018
Publisher: AIP Publishing
Date: 05-2008
DOI: 10.1063/1.2908183
Abstract: A new technique of wirelessly transmitting electric energy to piezoelectric components is explored. In the design, an ac electric field is focused to a piezoelectric plate placed between plate-shaped live and needle ground electrodes which form a capacitorlike electric field generator in series with an inductor. The transmission of electric energy is enhanced when the capacitorlike electric field generator and inductor are in electric resonance. Experimentally it has been found that the real output power delivered to the piezoelectric plate depends on the electrode pattern, vibration mode, and electrical load of the piezoelectric component and the electric field focused by the needle ground and live electrodes. When the operating frequency is close to mechanical resonance frequency of the piezoelectric plate operating in the thickness vibration mode, a maximum output power of 0.264W and energy conversion efficiency of 1.02% have been achieved with an input voltage 150Vrms and 10mm electrode separation.
Publisher: AIP Publishing
Date: 10-04-2014
DOI: 10.1063/1.4871399
Abstract: Consistency between x-ray photoelectron spectroscopy measurements and density-function theory calculations confirms our bond order-length-strength notation-incorporated tight-binding theory predictions on the quantum entrapment of Si solid skin and atomic clusters. It has been revealed that bond-order deficiency shortens and strengthens the Si-Si bond, which results in the local densification and quantum entrapment of the core and valence electrons. Unifying Si clusters and Si(001) and (111) skins, this mechanism has led to quantification of the 2p binding energy of 96.089 eV for an isolated Si atom, and their bulk shifts of 2.461 eV. Findings evidence the significance of atomic undercoordination that is of great importance to device performance.
Publisher: IOP Publishing
Date: 14-08-2000
Publisher: World Scientific Pub Co Pte Lt
Date: 30-08-1998
DOI: 10.1142/S0217984998000974
Abstract: A novel rhombi-chain network is derived from low energy electron diffraction experimental observations and the recent model theory, revealing that the O-Rh(100) clock-rotation is driven by an electrostatic force arisen from bond formation. Thus the O-Rh bond suffers from tension other than compression, or strain relief. As O -1 evolves into the hybridized- O -2 ,a Rh 5 O cluster in the c(2 × 2) phase develops into a Rh 4 O tetrahedron and yields the overall (2 × 2)p4g reconstruction. In the (2 × 2)p4g phase, the hollow-sited O -2 defines one Rh + ion and two lone-pair-induced Rh dipoles of its four surface neighbors. The surface atomic ratio (O : Rh = 1 : 2) allocates, therefore, half of the surface Rh atoms to be the Rh dipoles and another half to play dual roles of Rh + ion and Rh dipole. Interactions along the "dipole–dipole – Rh + /dipole – Rh + /dipole" strings create the rhombi-chain at the directions, and a responding bond tension confines the (2 × 2)p4g clock rotation.
Publisher: American Chemical Society (ACS)
Date: 13-07-2015
Abstract: Relaxation of the inter- and intra-molecular interactions for the hydrogen bond (O:H-O) between undercoordinated molecules determines the unusual behavior of water nanodroplets and nanobubbles. However, probing such potentials remains unreality. Here we show that the Lagrangian solution [Huang et al., J. Phys. Chem. B, 2013. 117: 13639] transforms the observed H-O bond (x = H) and O:H nonbond (x = L) lengths and phonon frequencies (dx, x) [Sun et al., J. Phys. Chem. Lett., 2013. 4: 2565] into the respective force constants and bond energies (kx, Ex) and hence enables the mapping of the potential paths for the O:H-O bond relaxing with water cluster size. Results show that molecular undercoordination not only reduces the molecular size (dH) with enhanced H-O energy from the bulk value of 3.97 to 5.10 eV for a H2O monomer, but also enlarges the molecular separation (dL) with reduced O:H energy from 95 to 35 meV for a dimer. The H-O energy gain raises the melting point from bulk value 273 to 310 K for the skin and the O:H energy loss lowers the freezing temperature from bulk value 258 to 202 K for 1.4 nm sized droplet, by dispersing the quasisolid phase boundaries.
Publisher: AIP Publishing
Date: 15-02-2002
DOI: 10.1063/1.1434546
Abstract: An approach improving diamond–metal adhesion has been developed based on modeling predictions and experimental verifications on the interfacial stresses modified by catalytic reaction. It is found that N-plasma irradiating onto Ti and tungsten-carbide substrates generates tensile surface stresses while C-plasma irradiation creates strongly compressive stress at the surfaces, both of which deteriorate the diamond–metal adhesion. It is also found that surface oxidation prevents diamond nucleation. Therefore, we applied a graded TiCN interlayer with carefully adjusting the ratio of C and N in the gas mixture to neutralize the interfacial stress and, hence, we have improved the diamond–metal adhesion substantially.
Publisher: IEEE
Date: 2001
Publisher: Elsevier BV
Date: 06-2019
Publisher: American Chemical Society (ACS)
Date: 08-05-2009
DOI: 10.1021/JP9035309
Publisher: American Chemical Society (ACS)
Date: 23-10-2018
DOI: 10.26434/CHEMRXIV.7233878.V1
Abstract: Charge injection in terms of alent cations and halide anions on the O:H-O network and properties with discrimination of the solute capabilities on transition O:H-O bonds from the mode of ordinary water of hydrating in terms of fraction number and stiffness.
Publisher: American Chemical Society (ACS)
Date: 09-10-2009
DOI: 10.1021/JP907726B
Publisher: Elsevier BV
Date: 05-2006
Publisher: MDPI AG
Date: 07-02-2018
DOI: 10.3390/NANO8020092
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SC20066J
Publisher: Elsevier BV
Date: 09-2015
Publisher: AIP Publishing
Date: 15-03-2010
DOI: 10.1063/1.3331958
Abstract: Although barium titanate (BaTiO3) ferroelectrics at the nanoscale has been extensively investigated, the physical origin of their unusual performance, in particular, the suppressed thermal stability remains yet unclear despite existing models from various perspectives. Based on the consideration of the short range bond order-length-strength correlation and the long range dipole-dipole interaction, we have developed a dual-shell model for the size and shape induced suppression of the Curie temperature for BaTiO3 nanocrystals. One surface shell of three atomic layers represents the short range interaction due to the shorter and stronger bonds between under-coordinated atoms, which intrinsically lowers the mean atomic cohesive energy of the crystal. The other shell with thickness of Kc (critical number of atomic layers) characterizes the long rang dipole-dipole interaction. If one moves a BaTiO3 unit cell from the center of the nanocrystal outwards, the unit cell will lose its ferroelectrics gradually upon reaching the Kc point. The modeling predictions have been verified by the presented experimental observations and results documented in the open literature. The least Kc has been optimized to be 9 for BaTiO3 spherical particles.
Publisher: Elsevier BV
Date: 2007
Publisher: IEEE
Date: 2006
Publisher: Elsevier BV
Date: 07-2016
Publisher: Elsevier BV
Date: 10-1997
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CY00452F
No related grants have been discovered for Changqing Sun.