ORCID Profile
0000-0001-7922-598X
Current Organisations
Argonne National Laboratory
,
Tsinghua University
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Publisher: AIP Publishing
Date: 19-04-2013
DOI: 10.1063/1.4802669
Abstract: We report changes in the metric symmetry of unpoled and electrically poled single crystals of 0.26Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.28PbTiO3, as revealed by neutron diffraction in conjunction with electrical measurements. The unpoled crystals show relaxor characteristics and an average rhombohedral symmetry that persists from ambient temperature up to the Curie temperature of ∼165 °C. Poling along a [111] direction enhances the rhombohedral distortion away from cubic metric symmetry but appears not to induce any monoclinic phases. By contrast, the poled [001]-oriented crystal has orthorhombic (or monoclinic MC) metric symmetry at 25 °C. An intermediate transition to a metrically tetragonal phase around 120 °C is confirmed for both poled crystals.
Publisher: Elsevier BV
Date: 09-2022
Publisher: Elsevier BV
Date: 11-2013
Publisher: AIP Publishing
Date: 19-08-2015
DOI: 10.1063/1.4927811
Abstract: Polarization domains in ferroelectric materials and the ability to orient them with an external electric field lead to the development of a variety of applications from information storage to actuation. The development of piezoresponse force microscopy (PFM) has enabled researchers to investigate ferroelectric domains and ferroelectric domain switching on the nanoscale, which offers a pathway to study structure-function relationships in this important material class. Due to its commercial availability and ease of use, PFM has become a widely used research tool. However, measurement artifacts, i.e., alternative signal origins besides the piezoelectric effect are barely discussed or considered. This becomes especially important for materials with a small piezoelectric coefficient or materials with unknown ferroelectric properties, including non-ferroelectric materials. Here, the role of surface charges and current flow during PFM measurements on classical ferroelectrics are discussed and it will be shown how they alter the PFM hysteresis loop shape. This will help to better address alternative signal origins in PFM-type experiments and offer a pathway to study additional phenomena besides ferroelectricity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CP00528K
Abstract: Strong electromechanical coupling in centrosymmetric organoruthenium complex due to disorder in molecular packing.
Publisher: American Chemical Society (ACS)
Date: 26-04-2021
Publisher: Elsevier BV
Date: 09-2017
Publisher: IOP Publishing
Date: 08-04-2015
DOI: 10.1088/0957-4484/26/17/175707
Abstract: Kelvin probe force microscopy (KPFM) is a powerful characterization technique for imaging local electrochemical and electrostatic potential distributions and has been applied across a broad range of materials and devices. Proper interpretation of the local KPFM data can be complicated, however, by convolution of the true surface potential under the tip with additional contributions due to long range capacitive coupling between the probe (e.g. cantilever, cone, tip apex) and the s le under test. In this work, band excitation (BE)-KPFM is used to negate such effects. In contrast to traditional single frequency KPFM, multifrequency BE-KPFM is shown to afford dual sensitivity to both the electrostatic force and the force gradient detection, analogous to simultaneous litude modulated and frequency modulated KPFM imaging. BE-KPFM is demonstrated on a Pt/Au/SiO(x) test structure and electrostatic force gradient detection is found to lead to an improved lateral resolution compared to electrostatic force detection. Finally, a 3D-KPFM imaging technique is developed. Force volume (FV) BE-KPFM allows the tip-s le distance dependence of the electrostatic interactions (force and force gradient) to be recorded at each point across the s le surface. As such, FVBE-KPFM provides a much needed pathway towards complete tip-s le capacitive de-convolution in KPFM measurements and will enable quantitative surface potential measurements with nanoscale resolution.
Publisher: European Association for Studies in Screen Translation
Date: 14-11-2018
DOI: 10.47476/JAT.V1I1.54
Abstract: We are proud to present the first issue of the Journal of Audiovisual Translation. Launching this new journal would not have been possible without the hard work of the Editorial Board members, much appreciated contributions from the Authors and support from ESIST and Scientific Board members. Audiovisual translation has come of age as a discipline in its own right and we strongly believe that it deserves a journal that is dedicated to this very specific field. Journal of Audiovisual Translation wishes to serve as an international forum and reference point for high-quality, innovative and in-depth research in all avenues of audiovisual translation studies.
Publisher: Wiley
Date: 05-04-2016
DOI: 10.1111/JACE.14227
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9MH00516A
Abstract: The introduction of defect-pairs into centrosymmetric rutile TiO 2 produces a new form of collective nonlinear electrical polarization.
Publisher: American Chemical Society (ACS)
Date: 08-08-2018
Abstract: In this report, a ferroelectric-luminescent heterostructure is designed to convert infrared light into electric power. We use BiFeO
Publisher: American Chemical Society (ACS)
Date: 16-12-2022
Publisher: AIP Publishing
Date: 09-03-2015
DOI: 10.1063/1.4913910
Abstract: A multifrequency open loop Kelvin probe force microscopy (KPFM) approach utilizing photothermal as opposed to electrical excitation is developed. Photothermal band excitation (PthBE)-KPFM is implemented here in a grid mode on a model test s le comprising a metal-insulator junction with local charge-patterned regions. Unlike the previously described open loop BE-KPFM, which relies on capacitive actuation of the cantilever, photothermal actuation is shown to be highly sensitive to the electrostatic force gradient even at biases close to the contact potential difference (CPD). PthBE-KPFM is further shown to provide a more localized measurement of true CPD in comparison to the gold standard ambient KPFM approach, litude modulated KPFM. Finally, PthBE-KPFM data contain information relating to local dielectric properties and electronic dissipation between tip and s le unattainable using conventional single frequency KPFM approaches.
Publisher: American Chemical Society (ACS)
Date: 09-03-2018
Abstract: The effect of above-band gap photons on the domains of the BiFeO
Publisher: Springer Science and Business Media LLC
Date: 24-11-2015
DOI: 10.1038/NCOMMS9985
Abstract: Elastic anomalies are signatures of phase transitions in condensed matters and have traditionally been studied using various techniques spanning from neutron scattering to static mechanical testing. Here, using band-excitation elastic iezoresponse spectroscopy, we probed sub-MHz elastic dynamics of a tip bias-induced rhombohedral−tetragonal phase transition of strained (001)-BiFeO 3 (rhombohedral) ferroelectric thin films from ∼10 3 nm 3 s le volumes. Near this transition, we observed that the Young’s modulus intrinsically softens by over 30% coinciding with two- to three-fold enhancement of local piezoresponse. Coupled with phase-field modelling, we also addressed the influence of polarization switching and mesoscopic structural heterogeneities (for ex le, domain walls) on the kinetics of this phase transition, thereby providing fresh insights into the morphotropic phase boundary in ferroelectrics. Furthermore, the giant electrically tunable elastic stiffness and corresponding electromechanical properties observed here suggest potential applications of BiFeO 3 in next-generation frequency-agile electroacoustic devices, based on the utilization of the soft modes underlying successive ferroelectric phase transitions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5NR04809E
Abstract: Variable temperature band-excitation atomic force microscopy in conjunction with I-V spectroscopy was used to investigate the crystalline superionic proton conductor CsHSO4 during proton exchange induced by a Pt-coated conductive scanning probe. At a s le temperature of 150 °C and under an applied bias <1 V, reduction currents of up to 1 nA were observed. Simultaneously, we show that the electrochemical reactions are accompanied by a reversible decrease in the elastic modulus of CsHSO4, as seen by a contact resonance shift, and find evidence for superplasticity during scanning. These effects were not observed in the room-temperature phase of CsHSO4 or in the case of catalytically inactive conductive probes, proving the utility of this technique for monitoring electrochemical processes on the nanoscale, as well as the use of local contact stiffness as a sensitive indicator of electrochemical reactions.
Publisher: AIP Publishing
Date: 25-03-2013
DOI: 10.1063/1.4794027
Abstract: Elastic and anelastic properties of poled and depoled single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 with compositions close to the morphotropic boundary have been investigated over the temperature range 5–700 K by resonant ultrasound spectroscopy (RUS) at frequencies of 0.1–1.2 MHz. Steep elastic softening occurs in a temperature interval of at least 250 K as the Vogel-Fulcher freezing interval and cubic → tetragonal transition point, Tc, are approached from above. This is understood in terms of coupling between acoustic modes and central peak mode(s) associated with dynamic polar nano regions (PNR's) below the Burns temperature. Acoustic losses occur in a temperature interval of ∼50 K above Tc, associated with slowing down of the PNR dynamics. The cubic ↔ tetragonal and tetragonal ↔ rhombohedral transitions are accompanied by steep minima in elastic properties, closely analogous to the pattern of softening and stiffening observed in sequences of improper ferroelastic transitions in other perovskites. Variations in the magnitudes of acoustic losses at T & Tc correlate with the density of ferroelastic twin walls, from lowest for [001]c-poled and [111]c-poled crystals in the stability fields of the tetragonal and rhombohedral phases, respectively, to highest for unpoled crystals. A simple model of Debye-like peaks in acoustic loss near 100 K has yielded activation energies and attempt frequencies in the same range as those observed from dielectric data in the Vogel-Fulcher freezing interval. These highlight the fact that, in addition to conventional ferroelectric/ferroelastic twin walls, relaxor ferroelectrics contain local structural heterogeneities coupled to strain, which are probably related to the presence of static PNR's preserved even in poled crystals. RUS also provides a convenient and effective means of determining the mechanical quality factor of relaxor ferroelectrics, as functions of both poling history and temperature.
Publisher: American Physical Society (APS)
Date: 15-06-2021
Publisher: Springer Science and Business Media LLC
Date: 11-01-2023
DOI: 10.1038/S41467-023-35877-7
Abstract: Defects in crystals play a fundamental role in modulating mechanical, electrical, luminescent, and magnetic behaviors of materials. However, accurate measurement of defect structures is hindered by symmetry breaking and the corresponding complex modifications in atomic configuration and/or crystal tilt at the defects. Here, we report the deep-sub-angstrom resolution imaging of dislocation cores via multislice electron ptychography with adaptive propagator, which allows sub-nanometer scale mapping of crystal tilt in the vicinity of dislocation cores and simultaneous recovery of depth-dependent atomic structure of dislocations. The realization of deep-sub-angstrom resolution and depth-dependent imaging of defects shows great potential in revealing microstructures and properties of real materials and devices.
Publisher: IOP Publishing
Date: 28-02-2012
DOI: 10.1088/0953-8984/24/12/125901
Abstract: This report details correlated electrical, mechanical and magnetic behaviour in BiFeO(3) ceramics doped with 10% Ln (Ln = Sm, Nd) ions on the Bi, or perovskite A, site and synthesized by a sol-gel method. The ceramics exhibit bulk piezoelectric and ferroelectric properties and clear ferroelectric domain patterns through piezoresponse force microscopy. Resonant ultrasound spectroscopy, dielectric spectroscopy and magnetometry studies show correlated magnetoelectromechanical behaviour and the existence of weak ferromagnetism for both compositions. An anomaly with simultaneous mechanical and magnetic signatures is discovered in both materials near room temperature, while previously reported transitions and anomalies are found to exhibit electro- and/or magnetomechanical coupling. Magnetism is significantly enhanced in the Sm doped s le, which is a promising multiferroic material.
Publisher: Wiley
Date: 31-07-2017
Abstract: Leveraging competition between energetically degenerate states to achieve large field-driven responses is a hallmark of functional materials, but routes to such competition are limited. Here, a new route to such effects involving domain-structure competition is demonstrated, which arises from strain-induced spontaneous partitioning of PbTiO
Publisher: American Chemical Society (ACS)
Date: 03-06-2022
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-03-2021
Abstract: Polymer-based ferroelectric materials are attractive because they can be solution processed cheaply and have much greater flexibility than ceramics. Guo et al. found concentric circular bands of polarization in a ferroelectric polymer that look like a bull's-eye target (see the Perspective by Martin). This self-organized toroidal texture is aligned perpendicularly to the axis of the polymer chains, allowing the authors to demonstrate selective absorption of infrared radiation and manipulation of terahertz radiation. This distinct structure in a polymer could be of interest for exploring and using other exotic effects. Science , this issue p. 1050 see also p. 992
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9MH01744E
Abstract: Intensive bulk photovoltaic effects are produced in narrow-bandgap centrosymmetric materials by a new strategy based on polar nano-regions.
Publisher: AIP Publishing
Date: 16-11-2015
DOI: 10.1063/1.4935977
Abstract: While electric field induced ferroelectric switching has been extensively studied and broadly utilized, pure mechanical switching via flexoelectric effect has recently opened up an alternative method for domain writing due to their highly localized, electrically erasable and electric damage free characteristics. Thus far, few studies have been made on the coupling effect of electro-mechanical switching in ferroelectric materials, likely due to the experimental difficulty in the accurate definition of the tip-surface contact area and in the identification of mechanical contribution from electrical effect. Here, we employed self-consistent phase-field modeling to investigate the bi-polar switching behavior of (001) oriented Pb(Zr0.2Ti0.8)O3 thin film under concurrent electric and strain field created via a piezoresponse force microscope probe. By separating the effects from electric field, homogeneous strain and strain gradient, we revealed that the homogeneous strain suppresses the spontaneous polarization and accordingly increases the coercive field, and the strain gradient favors unipolar switching and inhibit it in the reverse direction, thus causing lateral offset of the hysteresis loop. The uncertainty of flexoelectric coefficients and the influence of flexocoupling coefficients on switching have also been discussed. Our study could necessitate further understanding of the electric, piezoelectric, and flexoelectric contribution to the switching behavior in nanoscale ferroelectric oxides.
Publisher: Springer Singapore
Date: 17-12-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TA01577C
Abstract: An easy-to-implement chemical solution deposition route using EG and CA additives is demonstrated to fabricate phase-pure AgNbO 3 films on Pt/Ti/SiO 2 /Si substrates, where the films show an M 2 antiferroelectric phase at room temperature.
Publisher: Wiley
Date: 21-08-2015
Publisher: American Chemical Society (ACS)
Date: 21-01-2015
DOI: 10.1021/NN506753U
Abstract: Nanomechanical properties are closely related to the states of matter, including chemical composition, crystal structure, mesoscopic domain configuration, etc. Investigation of these properties at the nanoscale requires not only static imaging methods, e.g., contact resonance atomic force microscopy (CR-AFM), but also spectroscopic methods capable of revealing their dependence on various external stimuli. Here we demonstrate the voltage spectroscopy of CR-AFM, which was realized by combining photothermal excitation (as opposed to the conventional piezoacoustic excitation method) with the band excitation technique. We applied this spectroscopy to explore local bias-induced phenomena ranging from purely physical to surface electromechanical and electrochemical processes. Our measurements show that the changes in the surface properties associated with these bias-induced transitions can be accurately assessed in a fast and dynamic manner, using resonance frequency as a signature. With many of the advantages offered by photothermal excitation, contact resonance voltage spectroscopy not only is expected to find applications in a broader field of nanoscience but also will provide a basis for future development of other nanoscale elastic spectroscopies.
Publisher: American Chemical Society (ACS)
Date: 15-06-2018
Abstract: Strongly correlated vanadium dioxide (VO
Publisher: AIP Publishing
Date: 08-07-2013
DOI: 10.1063/1.4813541
Publisher: AIP Publishing
Date: 19-12-2013
DOI: 10.1063/1.4851815
Abstract: Real part of complex relative dielectric value is relatively decreased as large as ∼5 % from 50 K to 200 K in CaCu3Ti4O12, by applying a 6-T static magnetic field. CaCu3Ti4O12 is thus implied primarily by the negative magnetodielectric effect, as a unified dielectric system in which 1-D finite dipole chains of B-site titanium ions, coexist with a collective of polaron-like 3d-electrons of A-site copper ions: the dipole chains are thermally activated for lattice ionic polarization above 50 K, and suppressed by the short-range hop of these quasi-particles, while their long-range movement are for bulk electronic polarization above 151 K.
Publisher: AIP Publishing
Date: 11-03-2013
DOI: 10.1063/1.4795145
Abstract: We report a continuously tunable resistive switching behavior in Pt/BiFeO3/Nb-doped SrTiO3 heterostructure for ferroelectric memristor application. The resistance of this memristor can be tuned up to 5 × 105% by applying voltage pulses at room temperature, which exhibits excellent retention and anti-fatigue characteristics. The observed memristive behavior is attributed to the modulation effect of the ferroelectric polarization reversal on the width of depletion region and the height of potential barrier of the p-n junction formed at the BiFeO3/Nb-doped SrTiO3 interface.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 2022
Abstract: Antiferroelectrics have attracted increasing research interests in recent years due to both their great potential in energy storage applications and intriguing structural characteristics. However, the links between the electrical properties and structural characteristics of distorted perovskite antiferroelectrics are yet to be fully deciphered. Here, we adopt local-structure methods to elucidate the nanoscale atomic structure of AgNbO 3 -based antiferroelectrics and their structural evolution upon La doping. The local structural features including interatomic distance distributions and atomic displacements have been analyzed using neutron small-box pair distribution function (PDF) refinement in conjunction with large-box Reverse Monte Carlo modelling. Our results highlight the correlation of cation displacements in AgNbO 3 and its disruption by the incorporation of La, apparently in corroboration with the observed anomalous dielectric properties. Spatial ordering of cation vacancies is observed in La-doped AgNbO 3 s les, which coordinates with oxygen octahedral tilting to relieve lattice strain. These results provide renewed insights into the atomic structure and antiferroelectric phase instabilities of AgNbO 3 and relevant perovskite materials, further lending versatile opportunities for enhancing their functionalities.
Publisher: Wiley
Date: 27-04-2023
Abstract: Direct neutron detection based on semiconductor crystals holds promise to transform current neutron detector technologies and further boosts their widespread applications. It is, however, long impeded by the dearth of suitable materials in the form of sizeable bulk crystals. Here, high‐quality centimeter‐sized LiInP 2 Se 6 single crystals are developed using the Bridgman method and their structure and property characteristics are systematically investigated. The prototype detectors fabricated from the crystals demonstrate an energy resolution of 53.7% in response to α ‐particles generated from an 241 Am source and robust, well‐defined response spectra to thermal neutrons that exhibit no polarization or degradation effects under prolonged neutron/ γ ‐ray irradiation. The primary mechanisms of Se‐vacancy and In Li antisite defects in the carrier trapping process are also identified. Such insights are critical for further enhancing the energy resolution of LiInP 2 Se 6 bulk crystals toward the intrinsic level (≈8.6% as indicated by the chemical vapor transport‐grown thin crystals). These results pave the way for practically adopting LiInP 2 Se 6 single crystals in new‐generation solid‐state neutron detectors.
Publisher: Wiley
Date: 22-11-2016
Publisher: IEEE
Date: 08-2014
Publisher: Wiley
Date: 12-12-2016
Abstract: An FeGa@P(VDF-TrFE) wire-shaped magnetoelectric nanorobot is designed and fabricated to demonstrate a proof-of-concept integrated device, which features wireless locomotion and on-site triggered therapeutics with a single external power source (i.e., a magnetic field). The device can be precisely steered toward a targeted location wirelessly by rotating magnetic fields and perform on-demand magnetoelectrically assisted drug release to kill cancer cells.
Publisher: Wiley
Date: 22-07-2016
Abstract: The controlled exfoliation of hexagonal boron nitride (h-BN) into single- or few-layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h-BN. Here, we present an efficient strategy for the scalable synthesis of few-layered h-BN nanosheets (BNNS) using a novel gas exfoliation of bulk h-BN in liquid N2 (L-N2 ). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h-BN and the cryogenic L-N2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layers with a high mass yield of 16-20 %. N2 sorption and desorption isotherms show that the BNNS-10 exhibited a much higher specific surface area of 278 m(2) g(-1) than that of bulk BN (10 m(2) g(-1) ). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h-BN. Subseqently, the L-N2 penetrates into the interlayers of h-BN along the curling edge, followed by an immediate drastic gasification of L-N2 , further peeling off h-BN. This novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials in high yields.
Publisher: American Chemical Society (ACS)
Date: 17-01-2023
DOI: 10.1021/JACS.2C12877
Publisher: Springer Science and Business Media LLC
Date: 15-11-2018
DOI: 10.1038/S41467-018-07177-Y
Abstract: Organic–inorganic hybrid perovskites are promising candidates for the next-generation solar cells. Many efforts have been made to study their structures in the search for a better mechanistic understanding to guide the materials optimization. Here, we investigate the structure instability of the single-crystalline CH 3 NH 3 PbI 3 (MAPbI 3 ) film by using transmission electron microscopy. We find that MAPbI 3 is very sensitive to the electron beam illumination and rapidly decomposes into the hexagonal PbI 2 . We propose a decomposition pathway, initiated with the loss of iodine ions, resulting in eventual collapse of perovskite structure and its decomposition into PbI 2 . These findings impose important question on the interpretation of experimental data based on electron diffraction and highlight the need to circumvent material decomposition in future electron microscopy studies. The structural evolution during decomposition process also sheds light on the structure instability of organic–inorganic hybrid perovskites in solar cell applications.
Publisher: AIP Publishing
Date: 19-08-2020
DOI: 10.1063/5.0018373
Abstract: The development of electronic materials for storing electrical energy is a thriving research field, where the materials used in batteries, supercapacitors, and dielectric capacitors have attracted extensive interest in last decades. The dielectric capacitors showing unique characteristics such as high power density and large charge/discharge rate have been actively studied, where the antiferroelectrics demonstrate great potentials for dielectric energy storage applications by storing and releasing energy upon a reversible electric-field induced antiferroelectric–ferroelectric phase transition. Recently, lead-free antiferroelectric AgNbO3 has emerged as a promising candidate to substitute conventional lead-based antiferroelectrics (such as PbZrO3) in energy storage applications. The phase transition dynamics of AgNbO3 is driven by a complex sequence of oxygen octahedron tilting orders in addition to cation displacement, which can be effectively engineered by a doping strategy. In this article, we present a succinct overview of the phase transition mechanisms in AgNbO3-based ceramics and describe how the phase transition characteristics are affected by the dopants. By exploring the composition related average structure and local structural evolutions, we provide a view toward the goal of establishing a link between the phase transition and physical properties tailored for dielectric energy storage applications.
Publisher: Hindawi Limited
Date: 2013
DOI: 10.1155/2013/382140
Abstract: We characterized the temperature dependent ( ~ 25–200°C) electromechanical properties and crystal structure of Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 single crystals using in situ electrical measurement and neutron diffraction techniques. The results show that the poled crystal experiences an addition phase transition around 120°C whereas such a transition is absent in the unpoled crystal. It is also found that the polar order persists above the maximum dielectric permittivity temperature at which the crystal shows a well-defined antiferroelectric behavior. The changes in the electrical properties and underlying crystal structure are discussed in the paper.
Publisher: Springer Science and Business Media LLC
Date: 13-11-2017
DOI: 10.1038/S41467-017-01733-8
Abstract: Flexoelectricity refers to electric polarization generated by heterogeneous mechanical strains, namely strain gradients, in materials of arbitrary crystal symmetries. Despite more than 50 years of work on this effect, an accurate identification of its coupling strength remains an experimental challenge for most materials, which impedes its wide recognition. Here, we show the presence of flexoelectricity in the recently discovered polar vortices in PbTiO 3 /SrTiO 3 superlattices based on a combination of machine-learning analysis of the atomic-scale electron microscopy imaging data and phenomenological phase-field modeling. By scrutinizing the influence of flexocoupling on the global vortex structure, we match theory and experiment using computer vision methodologies to determine the flexoelectric coefficients for PbTiO 3 and SrTiO 3 . Our findings highlight the inherent, nontrivial role of flexoelectricity in the generation of emergent complex polarization morphologies and demonstrate a viable approach to delineating this effect, conducive to the deeper exploration of both topics.
Publisher: American Chemical Society (ACS)
Date: 02-10-2014
DOI: 10.1021/NN505176A
Abstract: The implementation of contact mode Kelvin probe force microscopy (cKPFM) utilizes the electrostatic interactions between tip and s le when the tip and s le are in contact with each other. Surprisingly, the electrostatic forces in contact are large enough to be measured even with tips as stiff as 4.5 N/m. As for traditional noncontact KPFM, the signal depends strongly on electrical properties of the s le, such as the dielectric constant, and the tip properties, such as the stiffness. Since the tip is in contact with the s le, bias-induced changes in the junction potential between tip and s le can be measured with higher lateral and temporal resolution compared to traditional noncontact KPFM. Significant and reproducible variations of tip-surface capacitance are observed and attributed to surface electrochemical phenomena. Observations of significant surface charge states at zero bias and strong hysteretic electromechanical responses at a nonferroelectric surface have significant implications for fields such as triboelectricity and piezoresponse force microscopy.
Publisher: American Chemical Society (ACS)
Date: 02-12-2020
Publisher: AIP Publishing
Date: 10-12-2012
DOI: 10.1063/1.4772511
Abstract: We report a method for switching spectroscopy Kelvin probe force microscopy (SS-KPFM). The method is established as a counterpart to switching spectroscopy piezoresponse force microscopy (SS-PFM) in Kelvin probe force microscopy. SS-KPFM yields quantitative information about the surface charge state during a local bias-induced polarization switching process, complementary to the electromechanical coupling properties probed via SS-PFM. Typical ferroelectric s les of a Pb-based relaxor single crystal and a BiFeO3 thin film were investigated using both methods. We briefly discuss the observed surface charging phenomena and their influence on the associated piezoresponse hysteresis loops.
Publisher: Oxford University Press (OUP)
Date: 31-05-2022
DOI: 10.1093/NSR/NWAC101
Publisher: AIP Publishing
Date: 22-07-2013
DOI: 10.1063/1.4816741
Abstract: In this study, the dielectric and ferroelectric switching behaviour of 0.5BaTiO3-0.5Bi(Mg1/2Ti1/2)O3 (BT-BMT) ceramics are investigated. The BT-BMT ceramic exhibits a typical dipolar-glass-like, dielectric polarisation relaxation. This is attributed to the 15 distinct possible local A4B2 configurations around the O ions and the effect this unavoidable local compositional variability has on the dipole relaxation behaviour of inherent 1-D ⟨111⟩ dipole chains, arising from correlated off-centre displacements of Bi3+ and Ti4+ ions along local ⟨111⟩ directions. On the other hand, switchable polarisation under strong applied electric fields is observed on different length scales accompanied by the appearance of strong polarisation relaxation, as observed via time-delayed piezoresponse hysteresis loop measurements. These experimental results demonstrate that this BT-BMT ceramic is relaxor ferroelectric in nature, although it exhibits dipolar-glass-like dielectric relaxation behaviour.
Publisher: Elsevier BV
Date: 03-2023
Publisher: Wiley
Date: 17-01-2013
Publisher: American Chemical Society (ACS)
Date: 06-05-2021
Publisher: Springer Science and Business Media LLC
Date: 14-04-2021
DOI: 10.1038/S41586-021-03342-4
Abstract: The collective dynamics of topological structures
No related grants have been discovered for Qian Li.