Search results for "Synchro"
showing 10 items of 886 documents
SPS-assisted preparation of the Magnéli phase WO2.90 for thermoelectric applications
2013
We describe the preparation and simultaneous consolidation of WO2.90 by spark plasma sintering (SPS). SPS allows for the direct manufacturing of large amounts of consolidated material. Synchrotron powder X-ray diffraction indicates that the material is single phase. Microstructure analysis indicates that the pellet is fully dense, allowing high-temperature thermoelectric properties to be reliably measured. The as-prepared samples of WO2.90 reach a ZT of 0.1 at 1100 K.
GdBO3 and YBO3 crystals under compression
2021
High-pressure X-ray diffraction studies on nanocrystals of the GdBO3 and YBO3 rare-earth orthoborates are herein reported up to 17.4(2) and 13.4(2) GPa respectively. The subsequent determination of the room-temperature pressure-volume equations of state is presented and discussed in the context of contemporary publications which contradict the findings of this work. In particular, the isothermal bulk moduli of GdBO3 and YBO3 are found to be 170(13) and 163(13) GPa respectively, almost 50% smaller than recent findings. Our experimental results provide an accurate revision of the high-pressure compressibility behaviour of GdBO3 and YBO3 which is consistent with the known systematics in isomor…
The mechanically activated combustion reaction in the Fe–Si system: in situ time-resolved synchrotron investigations
2002
Mechanical high-energy ball milling of Fe+2Si elemental powder mixtures was used to activate self sustaining combustion reaction in the case of iron disilicide synthesis. The reaction path as well as the influence of the microstructural parameters on phase transformation have been investigated in detail. Time-resolved X-ray diffraction (TRXRD) using the fast recording kinetics offered by the synchrotron radiation was coupled to an infrared camera in order to study the internal structure of the combustion wave. The crystallite size and the amount of mechanically induced phases play an important role during the combustion; the reaction path and the end product composition mainly depend on the…
Mechanically Activated SHS Reaction in the Fe-Al System: In Situ Time Resolved Diffraction Using Synchrotron Radiation
1998
The Mechanical Activation Self propagating High temperature Synthesis (M.A.S.H.S.) processing is a new way to produce nanocrystalline iron aluminide intermetallic compounds. This process is maily the combination of two steps ; in the one hand, a mechanical activation where the Fe - Al powder mixture was milled during a short time at given energy and frequency of shocks and in the other hand, a Self propagating High temperature Synthesis (S.H.S.) reaction, for which the exothermicity of the Fe + Al reaction is used. This fast propagated MASHS reaction has been in -situ investigated using the Time Resolved X - Ray Diffraction (TRXRD) using a X - ray synchrotron beam and an infrared thermograp…
Time-resolved XRD experiments for a fine description of mechanisms induced during reactive sintering
2005
The control of Mechanically Activated Field Activated Pressure Assisted Synthesis hereafter called the MAFAPAS process is the main objective to be achieved for producing nanostructure materials with a controlled consolidation level. Consequently, it was essential to develop characterization tools "in situ" such as the Time Resolved X-ray Diffraction (TRXRD), with an X-ray synchrotron beam (H10, LURE Orsay) coupled to an infrared thermography to study simultaneously structural transformations and thermal evolutions. From the 2003 experiments, we took the opportunity to modify the sample-holder in order to reproduce the better synthesis conditions of the MAFAPAS process, but without the conso…
Short and long range order of Half-Heusler phases in (Ti,Zr,Hf)CoSb thermoelectric compounds
2016
Abstract The structural properties of (Ti,Zr,Hf)CoSb thermoelectric Half-Heusler compounds were investigated by synchrotron radiation based techniques. The short-range order, in particular the environment of the Co atoms, was studied by extended X-Ray absorption fine structure spectroscopy and the long range order by powder X-Ray diffraction. Structural models were obtained for the single phase materials TiCoSb0.85Sn0.15, ZrCoSb0.85Sn0.15, and HfCoSb0.85Sn0.15. These models were transferred for the phase-separated material Ti0.5Hf0.5CoSb0.85Sn0.15. As a result, proving that each Half-Heusler phase was well ordered, apart from the intermixing of Ti and Hf on its designated crystallographic l…
Synchrotron diffraction study of the isothermal oxidation of uranium dioxide at 250°C
2003
ABSTRACTThe structural evolution of UO2 during its oxidation to U3O8 at 250°C in air was studied by in-situ synchrotron X-ray diffraction on the D2AM-CRG beamline at ESRF. The aim of this study is to determine the phases that are likely to appear during the long-term storage of spent nuclear fuel. Our results are in disagreement with the literature in which the existence of an intermediate cubic phase is not reported. Instead, an α-U3O7 tetragonal phase (c/a < 1) was mentioned but not definitively observed. These previous interpretations may have been the result of poor instrumental resolution.
Effect of Penetrating Irradiation on Polarization Reversal in PZT Thin Films
2006
Spatially non-uniform imprint behavior induced by X-ray synchrotron, electron, and neutron irradiation has been investigated in Pb(Zr,Ti)O3 thin films. The obtained effects have been explained as a result of acceleration of the bulk screening process induced by irradiation. It has been shown that the spatial distribution of the internal bias field is determined by the domain pattern existing during irradiation. The microstructural changes in the structural characteristics during fatigue cycling have been revealed by high resolution synchrotron X-ray diffraction experiments. Their correlation with the evolution of the switching characteristics has been revealed and discussed.
A study of KNbO3in the pressure range to 12 GPa using synchrotron radiation
1997
Abstract Orthorhombic KNbO3 has been studied by x-ray diffraction as a function of pressure. The lattice cell parameters, volume and stability range of this phase have been determined as a function of the applied pressure. No structural transformation has been observed up to 12 GPa. The resulting P-V data are fitted to a Murnaghan equation state of first-order.
High-energy X-ray diffraction and topography investigation of CdZnTe
2005
High-energy transmission x-ray diffraction techniques have been applied to investigate the crystal quality of CdZnTe (CZT). CdZnTe has shown excellent performance in hard x-ray and gamma detection; unfortunately, bulk nonuniformities still limit spectroscopic properties of CZT detectors. Collimated high-energy x-rays, produced by a superconducting wiggler at the National Synchrotron Light Source’s X17B1 beamline, allow for a nondestructive characterization of thick CZT samples (2–3 mm). In order to have complete information about the defect distribution and strains in the crystals, two series of experiments have been performed. First, a monochromatic 67 keV x-ray beam with the size of 300×3…