ORCID Profile
0000-0003-3961-5099
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Publisher: American Physical Society (APS)
Date: 12-09-2011
Publisher: Informa UK Limited
Date: 21-05-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1NJ00008J
Publisher: International Union of Crystallography (IUCr)
Date: 10-08-2016
DOI: 10.1107/S1600576716010657
Abstract: Voids can significantly affect the performance of materials and a key question is how voids form and evolve. Voids also provide a rare opportunity to study the fundamental interplay between surface crystallography and atomic diffusion at the nanoscale. In the present work, the shrinkage of voids in aluminium from 20 to 1 nm in diameter through in situ annealing is imaged in a transmission electron microscope. It is found that voids first shrink anisotropically from a non-equilibrium to an equilibrium shape and then shrink while maintaining their equilibrium shape until they collapse. It is revealed that this process maximizes the reduction in total surface energy per vacancy emitted. It is also observed that shrinkage is quantized, taking place one atomic layer and one void facet at a time. By taking the quantization and electron irradiation into account, the measured void shrinkage rates can be modelled satisfactorily for voids down to 5 nm using bulk diffusion kinetics. Continuous electron irradiation accelerates the shrinkage kinetics significantly however, it does not affect the energetics, which control void shape.
Publisher: American Chemical Society (ACS)
Date: 02-11-2017
Abstract: Recent advances in the ability to synthesize metallic nanoparticles with tailored geometries have led to a revolution in the field of plasmonics. However, studies of the important complementary system, an inverted nanostructure, have so far been limited to two-dimensional sphere-segment voids or holes. Here we reveal the localized surface plasmon resonances (LSPRs) of nanovoids that are topologically enclosed in three-dimensions: an "anti-nanoparticle". We combine this topology with the favorable plasmonic properties of aluminum to observe strongly localized field enhancements with LSPR energies in the extreme UV range, well beyond those accessible with noble metals or yet achieved with aluminum. We demonstrate the resonance tunability by tailoring the shape and size of the nanovoids, which are truncated octahedra in the 10-20 nm range. This system is pristine: the nanovoid cavity is free from any oxide or supporting substrate that would affect the LSPRs. We exploit this to infer LSPRs of pure, sub-20-nm Al nanoparticles, which have yet to be synthesized. Access to this extreme UV range will allow applications in LSPR-enhanced UV photoemission spectroscopy and photoionization.
Publisher: Elsevier BV
Date: 02-2017
Publisher: American Chemical Society (ACS)
Date: 24-05-2011
DOI: 10.1021/CG200397Z
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C005146M
Abstract: A monoclinic periodic mesoporous Li(x)(Mn(1/3)Ni(1/3)Co(1/3))O(2) spinel has been successfully prepared for the first time using a 'two solvents' pore infiltration methodology on hard silica templates. More commonly used synthetic techniques are not applicable to this complex material. This important battery cathode has a surface area of over 180 m(2)g(-1) and a pore size of 5.5 nm.
Publisher: AIP Publishing
Date: 25-09-2000
DOI: 10.1063/1.1313251
Abstract: The following features of multiwalled BN nanotubes were discovered using a field emission high-resolution analytical transmission electron microscope: (i) coexistence of hexagonal and rhombohedral stacking in nanotube shell assembly (ii) flattening of nanotube cross section, which makes possible clear atomic resolution of the core structure in a three-shelled nanotube and (iii) change in chirality of tubular layers from armchair to zigzag arrangement in a 30° double-walled nanotube kink, as revealed by atomically resolved images of tube wall segments.
Publisher: Elsevier BV
Date: 06-2017
Publisher: American Chemical Society (ACS)
Date: 20-12-2019
Publisher: Elsevier BV
Date: 06-2017
Publisher: Springer Science and Business Media LLC
Date: 31-08-2015
DOI: 10.1038/NMAT4390
Abstract: Self-assembled nanostructures with periodic phase separation hold great promise for creating two- and three-dimensional superlattices with extraordinary physical properties. Understanding the mechanism(s) driving the formation of such superlattices demands an understanding of their underlying atomic structure. However, the nanoscale structural fluctuations intrinsic to these superlattices pose a new challenge for structure determination methods. Here we develop an optimized atomic-level imaging condition to measure TiO6 octahedral tilt angles, unit-cell-by-unit-cell, in perovskite-based Li(0.5-3x)Nd(0.5+x)TiO3, and thereby determine the mathematical formula governing this nanoscale superstructure. We obtain a direct real-space correlation of the octahedral tilt modulation with the superstructure geometry and lattice-parameter variations. This reveals a composition-dependent, self-ordered octahedral superlattice. Amazingly, we observe a reversible annihilation/reconstruction of the octahedral superlattice correlated with the delithiation/lithiation process in this promising Li-ion conductor. This approach to quantify local octahedral tilt and correlate it with strain can be applied to characterize complex octahedral behaviours in other advanced oxide systems.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC02429C
Abstract: The first colloidal synthesis of Ge-doped ZnO nanocrystals is presented. Ge dopants induce a surface plasmon resonance in the infrared and affect the ZnO nanocrystal morphology.
Publisher: Springer Science and Business Media LLC
Date: 07-03-2007
Publisher: AIP Publishing
Date: 15-08-1999
DOI: 10.1063/1.371058
Abstract: Here we report on the precise structural investigation of multiwalled boron nitride (BN) nanotubes by means of high-resolution transmission electron microscopy and electron energy loss spectroscopy. The nanotubes were produced from carbon nanotubes by applying a recently discovered technique: a substitution chemical reaction [W. Han, Y. Bando, K. Kurashima, and T. Sato, Appl. Phys. Lett. 73, 3085 (1998)]. It is found that in contrast to the starting carbon nanotubes, which exhibited large number of shells (typically & ), a significant proportion of buckled and corrugated graphene-like sheets, poor degree of graphitization, and wide distribution of helicities, the resultant BN nanotubes revealed perfectly straight shapes, limited number of shells (typically 2–6), and remarkable ordering of the graphene-like sheets in the so-called nonhelical “zig-zag” fashion with the [101̄0] direction parallel to the tube axis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0PY00771D
Abstract: This work demonstrates that the high sensitivity of EELS can be used to identify the changes in the chemical structure of polymeric materials.
Publisher: Elsevier BV
Date: 2012
Publisher: American Chemical Society (ACS)
Date: 21-10-2011
DOI: 10.1021/JP204427J
Publisher: Informa UK Limited
Date: 09-2009
Publisher: Elsevier BV
Date: 1999
Publisher: Wiley
Date: 17-03-2012
Publisher: Elsevier BV
Date: 02-2019
Publisher: Elsevier BV
Date: 11-2011
Publisher: Informa UK Limited
Date: 21-08-2005
Publisher: Springer Science and Business Media LLC
Date: 20-04-2016
DOI: 10.1038/NCOMMS11335
Abstract: Ammonia (NH 3 ) is one of the most widely produced chemicals worldwide. It has application in the production of many important chemicals, particularly fertilizers. It is also, potentially, an important energy storage intermediate and clean energy carrier. Ammonia production, however, mostly uses fossil fuels and currently accounts for more than 1.6% of global CO 2 emissions (0.57 Gt in 2015). Here we describe a solar-driven nanostructured photoelectrochemical cell based on plasmon-enhanced black silicon for the conversion of atmospheric N 2 to ammonia producing yields of 13.3 mg m −2 h −1 under 2 suns illumination. The yield increases with pressure the highest observed in this work was 60 mg m −2 h −1 at 7 atm. In the presence of sulfite as a reactant, the process also offers a direct solar energy route to ammonium sulfate, a fertilizer of economic importance. Although the yields are currently not sufficient for practical application, there is much scope for improvement in the active materials in this cell.
Publisher: American Society of Hematology
Date: 14-09-2017
DOI: 10.1182/BLOOD-2017-02-764787
Abstract: Zoonotic P cynomolgi switches red cell tropism for reticulocytes expressing Trf1 (CD71+) and DARC (CD234+). In the human host, P cynomolgi displays an almost identical rheopathobiology to P vivax.
Publisher: Wiley
Date: 10-2010
Publisher: Springer International Publishing
Date: 2016
Publisher: Elsevier BV
Date: 08-2019
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 2000
Publisher: American Chemical Society (ACS)
Date: 13-09-2021
Publisher: Informa UK Limited
Date: 10-2001
Publisher: American Physical Society (APS)
Date: 18-05-2016
Publisher: International Union of Crystallography (IUCr)
Date: 09-07-2015
DOI: 10.1107/S2053273315011845
Abstract: The interpretation of angular symmetries in electron nanodiffraction patterns from thin amorphous specimens is examined. It is found that in general there are odd symmetries in experimental electron nanodiffraction patterns. Using simulation, it is demonstrated that this effect can be attributed to dynamical scattering, rather than other ergences from the ideal experimental conditions such as probe-forming lens aberrations and camera noise. The departure of opposing diffracted intensities from Friedel's law in the phase grating formalism is calculated using a general structure factor for disordered materials. On the basis of this, a simple correction procedure is suggested to recover the kinematical angular symmetries, and thus readily interpretable information that reflects the symmetries of the original projected object. This correction is numerically tested using both the phase object and multislice calculations, and is demonstrated to fully recover all the kinematical diffracted symmetries from a simulated atomic model of a metallic glass.
Publisher: Elsevier BV
Date: 12-2003
Publisher: Elsevier BV
Date: 12-2015
Publisher: Wiley
Date: 03-09-2007
Publisher: Elsevier BV
Date: 08-2008
Publisher: Elsevier BV
Date: 07-2020
Publisher: Springer International Publishing
Date: 2012
Publisher: American Chemical Society (ACS)
Date: 24-08-2009
DOI: 10.1021/CM901757H
Publisher: Wiley
Date: 16-04-2014
Abstract: Aging in super glassy polymers such as poly(trimethylsilylpropyne) (PTMSP), poly(4-methyl-2-pentyne) (PMP), and polymers with intrinsic microporosity (PIM-1) reduces gas permeabilities and limits their application as gas-separation membranes. While super glassy polymers are initially very porous, and ultra-permeable, they quickly pack into a denser phase becoming less porous and permeable. This age-old problem has been solved by adding an ultraporous additive that maintains the low density, porous, initial stage of super glassy polymers through absorbing a portion of the polymer chains within its pores thereby holding the chains in their open position. This result is the first time that aging in super glassy polymers is inhibited whilst maintaining enhanced CO2 permeability for one year and improving CO2/N2 selectivity. This approach could allow super glassy polymers to be revisited for commercial application in gas separations.
Publisher: Wiley
Date: 17-04-2012
Publisher: Elsevier BV
Date: 02-2016
Publisher: Elsevier BV
Date: 08-2005
Publisher: Elsevier BV
Date: 12-2009
Publisher: Elsevier BV
Date: 12-2017
Publisher: IOP Publishing
Date: 04-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC17078G
Abstract: We synthesised a novel gold-on-porous silicon hybrid material that exhibits a highly sensitive and reproducible surface-enhanced Raman spectroscopy (SERS) response. The material was fabricated simply by reducing gold chloride with hydrofluoric acid on the surface of macro-porous silicon (macro-PSi). The material consists of thorn-shaped gold nanocrystals with characteristic shapes and sizes on the surface of macro-PSi.
Publisher: American Physical Society (APS)
Date: 09-06-2016
Publisher: IOP Publishing
Date: 21-02-2007
Publisher: Wiley
Date: 26-01-2009
Abstract: Nanochannel alumina templates are used as templates for fabrication of porous gold nanowire arrays by a direct electrodeposition method. After modification with glucose oxidase, a porous gold nanowire-array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose. The picture shows an SEM image of a nanowire array after removal of the alumina template by acid dissolution. We report the fabrication of porous gold nanowire arrays by means of a one-step electrodeposition method utilizing nanochannel alumina templates. The microstructure of gold nanowires depends strongly on the current density. The formation of porous gold nanowires is attributed to disperse crystallization under conditions of low nucleation rate. Interfacial electron transport through the porous gold nanowires is studied by electrochemical impedance spectroscopy. Cyclic voltammetric studies on the porous gold nanowire arrays reveal a low-potential electrocatalytic response towards hydrogen peroxide. The properties of the glucose oxidase modified porous gold nanowire array electrode are elucidated and compared with those of nonporous enzyme electrodes. The glucose oxidase modified porous gold nanowire-array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose.
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.ULTRAMIC.2010.12.004
Abstract: State-of-the art atom probe tomography (APT) combined with transmission electron microscopy (TEM) were used to investigate the microstructure at different stages of the ageing process of an alloy of composition (at%) Al-1.68%Cu-4.62%Li-0.33%Mg-0.1%Ag. These alloys were shown to exhibit a complex microstructure of T(1) plates and several metastable phases, including θ' and S. We will highlight the early stages of clustering, precipitate interactions and possible solute segregation at the matrix recipitate interfaces and detail the chemical composition of the different phases.
Publisher: American Physical Society (APS)
Date: 25-07-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TB00659G
Abstract: Herein we demonstrate the green synthesis of fluorescent gold nanoclusters (AuNCs) using a multi-responsive intrinsically disordered protein (IDP) polymer, Rec1-resilin, as a multi-functional template.
Publisher: Elsevier BV
Date: 07-2011
DOI: 10.1016/J.ULTRAMIC.2011.03.007
Abstract: Single defocused transmission electron microscope phase contrast images are used to reconstruct the projected thickness map of a single-material object. The algorithm is non-iterative and stable, and we extend it to account for the presence of spherical aberration in the objective optics. The technique can reconstruct the projected thickness map of general single-material objects in the strong phase/weak litude regime. It is sensitive to any excursions in the projected thickness from the average, and ideal for examining voids and free volume accumulation in amorphous/glassy materials at the nanometer scale. The resolution of the technique depends on the choice of defocus and the thickness of the specimen. In a certain regime, we demonstrate that variations in the transverse projected thickness with a lateral diameter of ∼ 0.25 nm may be detected. We use our algorithm to quantitatively reconstruct the projected thickness of latex sphere test specimens from single defocused electron micrographs. We demonstrate that the reconstruction has a large tolerance for error in the input parameters. Simulations confirm that the technique is quantitative, and demonstrate that the origin of low-frequency artifacts is an instability due to noise. We show that the autocorrelation of the projected thickness map may be used to measure the size of open structures in the object using both simulation and latex sphere data.
Publisher: American Chemical Society (ACS)
Date: 29-05-2018
DOI: 10.1021/ACS.LANGMUIR.8B00401
Abstract: Metal-semiconductor hybrid nanomaterials are becoming increasingly popular for photocatalytic degradation of organic pollutants. Herein, a seed-assisted photodeposition approach is put forward for the site-specific growth of Pt on Au-ZnO particles (Pt-Au-ZnO). A similar approach was also utilized to enlarge the Au nanoparticles at epitaxial Au-ZnO particles (Au@Au-ZnO). An epitaxial connection at the Au-ZnO interface was found to be critical for the site-specific deposition of Pt or Au. Light on-off photocatalysis tests, utilizing a thiazine dye (toluidine blue) as a model organic compound, were conducted and confirmed the superior photodegradation properties of Pt-Au-ZnO hybrids compared to Au-ZnO. In contrast, Au-ZnO type hybrids were more effective toward photoreduction of toluidine blue to leuco-toluidine blue. It was deemed that photoexcited electrons of Au-ZnO (Au, ∼5 nm) possessed high reducing power owing to electron accumulation and negative shift in Fermi level/redox potential however, exciton recombination due to possible Fermi-level equilibration slowed down the complete degradation of toluidine blue. In the case of Au@Au-ZnO (Au, ∼15 nm), the photodegradation efficiency was enhanced and the photoreduction rate reduced compared to Au-ZnO. Pt-Au-ZnO hybrids showed better photodegradation and mineralization properties compared to both Au-ZnO and Au@Au-ZnO owing to a fast electron discharge (i.e. better electron-hole seperation). However, photoexcited electrons lacked the reducing power for the photoreduction of toluidine blue. The ultimate photodegradation efficiencies of Pt-Au-ZnO, Au@Au-ZnO, and Au-ZnO were 84, 66, and 39%, respectively. In the interest of effective metal-semiconductor type photocatalysts, the present study points out the importance of choosing the right metal, depending on whether a photoreduction and/or photodegradation process is desired.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2DT00023G
Abstract: An integrated suite of synthesis and characterisation techniques that includes synchrotron-based single crystal, powder X-ray diffraction, nuclear magnetic resonance and electron diffraction have been employed to uncover two new distinct structures in the Ca(x)Ba(2-x)P(2)O(7) polymorphic phosphate system. These materials have particular relevance for their application as both biomaterials and phosphors. Calcium barium pyrophosphate, CaBaP(2)O(7), was shown by a combination of spectroscopic and diffraction techniques to have two polymorphs distinct in structure from all of the five previously reported polymorphs of Ca, Sr and Ba pyrophosphate. A high temperature polymorph HT-CaBaP(2)O(7) prepared at 1200 °C is orthorhombic, of space group P(212121) with a = 13.0494 Å, b = 8.9677 Å, c = 5.5444 Å. A low temperature polymorph LT-CaBaP(2)O(7), prepared below 1000 °C, is monoclinic with space group P2(1)/c and dimensions a = 12.065 Å, b = 10.582 Å, c = 9.515 Å, β = 94.609°.
Publisher: Elsevier BV
Date: 04-2010
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 08-2009
Publisher: Elsevier BV
Date: 10-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B903791H
Publisher: Elsevier BV
Date: 05-2014
Publisher: Elsevier BV
Date: 06-2014
Publisher: Elsevier BV
Date: 10-2012
Publisher: American Chemical Society (ACS)
Date: 15-11-2013
DOI: 10.1021/JP408055G
Publisher: Oxford University Press (OUP)
Date: 1999
Publisher: Elsevier BV
Date: 12-2008
Publisher: IOP Publishing
Date: 27-05-2016
Publisher: American Chemical Society (ACS)
Date: 22-10-2018
DOI: 10.1021/ACS.NANOLETT.8B03398
Abstract: Research on electromechanical properties of semiconducting nanowires, including plastic behavior of Si nanowires and superb carrier mobility of Ge and Ge/Si core-shell nanowires, has attracted increasing attention. However, to date, there have been no direct experimental studies on crystallography dynamics and its relation to electrical and mechanical properties of Ge/Si core-shell nanowires. In this Letter, we in parallel investigated the crystallography changes and electrical and mechanical behaviors of Ge/Si core-shell nanowires under their deformation in a transmission electron microscope (TEM). The core-shell Ge/Si nanowires were bent and strained in tension to high limits. The nanowire Young's moduli were measured to be up to ∼191 GPa, and tensile strength was in a range of 3-8 GPa. Using high-resolution imaging, we confirmed that under large bending strains, Si shells had irregularly changed to the polycrystalline/amorphous state, whereas Ge cores kept single crystal status with the local lattice strains on the compressed side. The nanowires revealed cyclically changed electronic properties and had decent mechanical robustness. Electron diffraction patterns obtained from in situ TEM, paired with theoretical simulations, implied that nonequilibrium phases of polycrystalline/amorphous Si and β-Sn Ge appearing during the deformations may explain the regarded mechanical robustness and varying conductivities under straining. Finally, atomistic simulations of Ge/Si nanowires showed the pronounced changes in their electronic structure during bending and the appearance of a conductive channel in compressed regions which might also be responsible for the increased conductivity seen in bent nanowires.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TA00398B
Abstract: Using Ag–Ag 8 GeS 6 as a model system, a novel strategy for the formation of Ag-based Janus nanostructures is presented.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Springer Science and Business Media LLC
Date: 06-03-2020
DOI: 10.1038/S41467-020-15087-1
Abstract: Many phase transformations associated with solid-state precipitation look structurally simple, yet, inexplicably, take place with great difficulty. A classic case of difficult phase transformations is the nucleation of strengthening precipitates in high-strength lightweight aluminium alloys. Here, using a combination of atomic-scale imaging, simulations and classical nucleation theory calculations, we investigate the nucleation of the strengthening phase θ′ onto a template structure in the aluminium-copper alloy system. We show that this transformation can be promoted in s les exhibiting at least one nanoscale dimension, with extremely high nucleation rates for the strengthening phase as well as for an unexpected phase. This template-directed solid-state nucleation pathway is enabled by the large influx of surface vacancies that results from heating a nanoscale solid. Template-directed nucleation is replicated in a bulk alloy as well as under electron irradiation, implying that this difficult transformation can be facilitated under the general condition of sustained excess vacancy concentrations.
Publisher: American Physical Society (APS)
Date: 14-02-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0EE00522C
No related grants have been discovered for Laure Bourgeois.