Search results for "X-ray"
showing 10 items of 4234 documents
Pressure-induced transition in titanium metal: a systematic study of the effects of uniaxial stress
2005
Abstract The effects of uniaxial stress on the pressure-induced α → ω transition in pure titanium (Ti) are investigated by means of angle dispersive X-ray diffraction in a diamond-anvil cell. Experiments under four different pressure environments reveal that: (1) the onset of the transition depends on the pressure medium used, going from 4.9 GPa (no pressure medium) to 10.5 GPa (argon pressure medium); (2) the α and ω phases coexist over a rather large pressure range, which depends on the pressure medium employed; (3) the hysteresis and quenchability of the ω phase is affected by differences in the sample pressure environment; and (4) a short-term laser heating of Ti lowers the α → ω transi…
XAFS analysis of the low symmetry octahedral molybdenum and tungsten oxides
1995
Abstract Comparative XAFS analysis of the main isostructural crystalline phases of W(Mo)O3 oxides and W(Mo)O3·nH2O hydrates has been done at the W L3 and Mo K edges. These compounds have (1) 3D perovskite-type (PT) structure (m-WO3); (2) 2D PT structure (WO3·H2O and MoO3·nH2O (n = 1,2)); (3) 2D hexagonal-type structure (WO3·1/3H2O) and (4) 2D double layered structure (α-MoO3). The detailed analysis of X-ray absorption fine structure (XAFS) in the low-symmetry structures shows that in order to simulate the experimental spectrum, it is sufficient to take into account single-scattering contributions in the range from 1.7 to ∼ 5.0 A and a number of multiple-scattering paths from nearly linear a…
LiCrO2 Under Pressure: In-Situ Structural and Vibrational Studies
2018
The high-pressure behaviour of LiCrO2, a compound isostructural to the battery compound LiCoO2, has been investigated by synchrotron-based angle-dispersive X-ray powder diffraction, Raman spectroscopy, and resistance measurements up to 41, 30, and 10 Gpa, respectively. The stability of the layered structured compound on a triangular lattice with R-3m space group is confirmed in all three measurements up to the highest pressure reached. The dependence of lattice parameters and unit-cell volume with pressure has been determined from the structural refinements of X-ray diffraction patterns that are used to extract the axial compressibilities and bulk modulus by means of Birch&ndash
CuInS2 Films for Photovoltaic Applications Deposited by a Low-Cost Method.
2006
We report an atmospheric-pressure deposition method for preparing well-adhered and compact CuInS 2 films. The precursor film is obtained by a solution-coating technique and is subjected to a low-cost and safe one-step reduction-sulfurization treatment. A maximum thickness of 300 nm is achieved per layer, and up to three layers were sulfurized at a time. The obtained films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and visible-near-infrared (vis-NIR) spectrophotometry.
CADEM: calculate X-ray diffraction of epitaxial multilayers
2017
This article presents a powerful yet simple program, based on the general one-dimensional kinematic X-ray diffraction (XRD) theory, which calculates the XRD patterns of tailor-made multilayers and thus enables quantitative comparison of measured and calculated XRD data. As the multilayers are constructed layer by layer, the final material stack can be entirely arbitrary.
<title>Laser-pulse-induced chemical reactions and surface patterning in Co-Si and Co-Ti-Si films: investigations by x-ray diffraction and atomi…
2001
X-ray diffraction patterns reflected from the laser treated crystalline CoSi2 layer, the measurements of surface electrical resistance and atomic force microscopy micrographs confirm the 'generation-diffusion-deformational instabilities' model of formation of defect ordered structures of various types. The CO2 laser induced decrease of the thermal coefficient of resistance to zero in Co-Ti-Si films is realized. X-ray diffraction studies of the treated films confirm that the obtained (alpha) changes with number of laser pulses are caused due to solid phase reaction Co + 2Si equals CoSi2 and 5Ti + 3Si equals Ti5Si3.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Do…
Electron diffraction, X-ray powder diffraction and pair-distribution-function analyses to determine the crystal structures of Pigment Yellow 213, C23…
2009
The crystal structure of the nanocrystalline alpha phase of Pigment Yellow 213 (P.Y. 213) was solved by a combination of single-crystal electron diffraction and X-ray powder diffraction, despite the poor crystallinity of the material. The molecules form an efficient dense packing, which explains the observed insolubility and weather fastness of the pigment. The pair-distribution function (PDF) of the alpha phase is consistent with the determined crystal structure. The beta phase of P.Y. 213 shows even lower crystal quality, so extracting any structural information directly from the diffraction data is not possible. PDF analysis indicates the beta phase to have a columnar structure with a si…
Chirality and electronic structure of the thiolate-protected Au38 nanocluster.
2010
Structural, electronic, and optical properties of the thiolate-protected Au(38)(SR)(24) cluster are studied by density-functional theory computations (R = CH(3) and R = C(6)H(13)) and by powder X-ray crystallography (R = C(12)H(25)). A low-energy structure which can be written as Au(23)@(Au(SR)(2))(3)(Au(2)(SR)(3))(6) having a bi-icosahedral core and a chiral arrangement of the protecting gold-thiolate Au(x)(SR)(y) units yields an excellent match between the computed (for R = C(6)H(13)) and measured (for R = C(12)H(25)) powder X-ray diffraction function. We interpret in detail the electronic structure of the Au(23) core by using a particle-in-a-cylinder model. Although the alkane thiolate l…
X-ray diffraction, optical birefringence, and87Rb nuclear magnetic resonance spectroscopy of the paraelectric and antiferroelectric phases of Rb3DxH1…
2002
The antiferroelectric (AFE) phase transition of Rb3DxH1-x(SO4)2 was studied using x-ray diffraction, optical birefringence, and nuclear magnetic resonance. The orientation dependence of the resonance lines deduced from the quadrupole-perturbed 87Rb nuclear magnetic resonance of Rb3D(SO4)2 single crystals indicates slight deviations from the monoclinic symmetry in the paraelectric and the AFE phases. The dynamical critical exponents as deduced from measurements of the spin-lattice relaxation times depend on the deuteron concentration. Additionally, we have carried out x-ray single-crystal diffraction as well as optical birefringence measurements and find clear evidence for a structural phase…
Simultaneous IR and time-resolved X-ray diffraction measurements for studying self-sustained reactions.
1998
Self-propagating high-temperature synthesis provides an attractive practical method for producing advanced materials such as ceramics, composites and intermetallics. This kind of reaction has been investigated in situ using time-resolved X-ray diffraction, with an X-ray synchrotron beam (D43 beamline, LURE, Orsay) coupled to simultaneous IR thermography to study structural transformations and thermal evolution. With short acquisition times (30 ms per pattern) it has been possible to observe several steps before obtaining compounds. Two different compound formations have been described: (i) the different steps of reaction, aluminium melting, subsequent temperature increase and fast reaction …