Publications by Philippe Buffat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

A review of experimental results obtained by different techniques is presented on the problem of zinc diffusion. Zinc diffusion was carried out on Si-doped GaAs (n almost-equal-to 10(18) cm-3) and on multiple quantum well (MQW) structures. The samples were investigated by secondary-ion mass spectroscopy (SIMS), different imaging modes of scanning electron microscopy such as secondary electrons, cathodoluminescence (CL) and electron beam-induced current (EBIC), transmission electron microscopy on a wedge-sha

The main strengthening mechanism for Inconel 718 (IN718), a Ni-based superalloy, is precipitation hardening by gamma ' and gamma '' particles. It is thus essential, for good alloy performance, that precipitates with the desired chemical composition have ad ...

Microstructure, chemical and phase composition of the hard layer formed on the Ti-6Al-4V alloy after duplex surface treatment were investigated by light microscopy (LM), X-ray diffraction (XRD) and analytical scanning, transmission and scanning transmissio ...

A comparative characterization of the structure of normal and abnormal (osteoporotic) human lumbar and thoracic vertebrae samples was carried out to reveal the type of possible disorder. Samples from the bone fragments extracted during the surgery due to v ...

Microporous limestones composed of micrite crystals constitute sizeable hydrocarbon reservoirs throughout the world and especially in the Middle East. However, the crystallization history of micrites is poorly understood. Scanning electronic microscopy (SE ...

Polyethylene block-copolymer films containing negative anhydride groups were used to immobilize TiO2, Fe2O3, and Fe3+ photocatalysts. The kinetics of the mineralization of azo-dye Orange II and chlorophenols on copolymer−TiO2, copolymer−Fe2O3, and copolymer−Fe3+ have been tested under optimized experimental conditions. In the case of copolymer−TiO2, the degradation kinetics for the model organic compounds were about the same as those observed with TiO2 suspensions containing about a 27 times higher amount o

Metamorphic InxAl1-xAs buffer design features influence on electrophysical and structural properties of the heterostructures was investigated. Two types of MHEMT heterostructures In0.70Al0.30As/In0.76Ga0.24As with novel design contained inverse steps or st ...

Dispersed Ag nanoparticles were prepared in aqueous solutions in the presence of pure poly[2-(dimethylamino)ethyl methacrylate] (poly-DMAEMA), poly[2-deoxy-2-methacrylamido-d-glucose] (poly-MAG), and their copolymers of poly[MAG–DMAEMA] with different mole ...

Synthesis of Pd nanoparticles with controlled size (d(Pd) = 1-3.6 nm) was carried out within the pores of the mesoporous HMS and SBA-15 silicas. Pd was ion-exchanged on non-calcined silicas, prepared by solvent extraction of the templates. A high concentration of silanol groups on the mesopore surface allowed attaining Pd loading up to 4.4. wt.%. The Pd/HMS and Pd/SBA-15 were characterised by chemical analysis, XRD, N2 adsorption-desorption and transmission electron microscopy (TEM) methods. The materials p

This paper reports a novel topotactic exchange reaction of the ethylenediammonium intercalated mixed-valent vanadyl phosphate, (H3NCH2CH2NH3)0.5[V4+0.45V5+0.55O2PO4{P(OH)2}0.483], with monovalent cations at room temperature. Alkali metal ions and other mon ...

A comparative characterization of crystal structure, morphology, sizes, and orientation in Ca phosphate precipitation from aqueous solutions, the mineral phase in bones, and mineral deposits on cardiac valves has been performed by high-resolution transmission electron microscopy to model possible mechanisms of Ca loss by bones. Physiological changes occurring in organisms can lead to deep perturbations of the natural calcium phosphate supersaturation and its local distribution, which in turn influences the

Thin film multilayers play a crucial role in the efficient transport of neutrons from the source to the experiments at the Swiss Neutron Spallation source SINQ. In order to develop and optimize the neutron optical components, a magnetron sputtering facility has been installed at PSI aimed at the deposition of thin films covering large substrate area. Initial uniformity tests are very encouraging showing thickness variation of only 1% for 5 nm layers over an area of 500 X 400 mm2. A detailed study of the str

With the idea of operating the factors affecting the mobility or the pinning of ferroelectric domain walls in AB03 perovskites, high resolution electron microscopy has been performed to provide a better knowledge of the walls themselves in PbTiO/sub 3/. The transition between two domains with their polarisation vectors at right angles appears to be along the (101) twin planes. The Maxwell equations can be satisfied by a highly localized space charge rather than a lattice distortion. As the heavy atom Pb lat

Sodium salts such as Na2CO3 and Na molybdate are active and selective MeOH dehydrogenation catalysts for the prodn. of water-free HCHO. Profound chem. and structural changes are experienced by the molybdate when employed under normal reaction conditions (500-700 Deg). The material reacts with the fluid phase and undergoes sepn. into Na2CO3 and Mo2C. The transition occurs relatively slowly and correlates well with start-up behavior of a catalytic fixed-bed reactor showing that an induction period is required

This work reports experimental results of the quantitative determination of oxygen and band gap measurement in the TiNx electrodes in planar TiNx top/La:HfO2/TiNx bottom MIM stacks obtained by plasma enhanced atomic layer deposition on SiO2. Methodological ...

Multiferroic materials with coexisting ferroelectric and ferromagnetic orders have attracted much attention due to the magnetoelectric coupling opening alternative prospects for electronic devices. Composite multiferroics containing separate ferroelectric ...

The response of Y2O3 nanoprecipitates in a 1-mu m YBa2Cu3O7-x layer from a superconducting wire Ag/YBCO/buffer metal oxides/Hastelloy to 107 MeV Kr and 167 MeV Xe ion irradiation was investigated using a combination of transmission electron microscopy, dif ...

The electron microscopy community makes a wide use of Energy Dispersive X-ray Spectrometry (EDS) for elemental mapping in STEM. This technique was however long reckoned slow, dozens of minutes if not an hour, to collect enough information for one map. Recent instrumental advances have dramatically changed the situation, reducing the acquisition time to minutes, improving the maps quality and boosting their spatial resolution beyond the nanometer scale or even down to the single atom column in crystalline ma

Surface processing of a Ti–6Al–4V alloy led to a complex multilayered microstructure containing several phases of the Ni–Ti–P–Al–O system, which improves the mechanical and tribological surface properties. The microstructure, chemical and phase composition ...

High-resolution transmission electron microscopy (HRTEM), electron microdiffraction, and X-ray diffraction were used to study hydroxyapatite specimens with particle sizes from a few nanometers to several hundreds of nanometers. Diffuse scattering (without clear reflections in transmission diffraction patterns) or strongly broadened peaks in X-ray diffraction patterns are characteristic for agglomerated hydroxyapatite nanocrystals. However, HRTEM and microdiffraction showed that this cannot be considered as

Philippe Buffat

Chat with Graph Search

Zinc Diffusion in Gaas and Zinc-Induced Disordering of Gaas Algaas Multiple Quantum-Wells - a Multitechnique Study

Composition and Element Distribution Mapping of γ′ and γ" Phases of Inconel 718 by High-Resolution Scanning Transmission Electron Microscopy and X-ray Energy-Dispersive Spectrometry

Phase analysis of multilayered, nanostructured titanium-base alloys by analytical electron microscopy

Scanning and transmission electron microscopy for evaluation of order/disorder in bone structure

TEM study of Mg distribution in micrite crystals from the Mishrif reservoir Formation (Middle East, Cenomanian to Early Turonian)

Photodynamics and surface characterization of TiO2 and Fe2O3 photocatalysts immobilized on modified polyethylene films

Metamorphic InAlAs/InGaAs/InAlAs/GaAs HEMT heterostructures containing strained superlattices and inverse steps in the metamorphic buffer

Mechanism of formation of silver nanoparticles in MAG-DMAEMA copolymer aqueous solutions

Pd/SiO2 catalysts: synthesis of Pd nanoparticles with the controlled size in mesoporous silicas

Novel topotactic conversion of an organically templated vanadyl phosphate framework into layered structures

Model of the mechanism of Ca loss by bones under microgravity and earth conditions

Thin Films for Neutron Optics

Study of ferroelectric domain walls in PbTiO/sub 3/ by high resolution microscopy and image simulation on a Cray-1S

Chemical and structural changes of sodium molybdate (Na2MoO4) as a methanol dehydrogenation catalyst

Structure, Oxygen Content and Electric Properties of Titanium Nitride Electrodes in TiNx/La:HfO2/TiNx Stacks Grown by PEALD on SiO2/Si

Search for Magnetoelectric Coupling at the Fe-57/Hf0.5Zr0.5O2 Interface Using Operando Synchrotron Mossbauer Spectroscopy

Effects of Kr and Xe ion irradiation on the structure of Y2O3 nanoprecipitates in YBCO thin film conductors

Recent EDS instrumental advances in STEM: from principles to applications

Characterisation of phases in nanostructured, multilayered titanium alloys by analytical and high-resolution electron microscopy

Size effect in X-ray and electron diffraction patterns from hydroxyapatite particles