J Phys Condens Matter
May 2024
This study performs extended x-ray absorption fine structure (EXAFS) measurements for the S-K edge in the temperature range of 10 and 300 K in the transmission mode using a photodiode to detect the transmitted x-rays. It provides the first report of temperature variations in the structural parameters of-S. As the temperature increases from 10 to 300 K in the Fourier transform ofkχ(k)the first peak corresponding to the covalent bond of the eight-membered ring becomes slightly low anomalously despite thermal disturbances.
View Article and Find Full Text PDFThe in situ X-ray absorption fine structure (XAFS) for the structural changes of Ag clusters produced in the cavity of luminescent zeolites by thermal treatment of Ag zeolite-A and Ag zeolite-X has been studied. The following procedures are compared: (i) samples are heated and cooled to room temperature under atmosphere (under air); (ii) samples are heated and cooled to room temperature in a vacuum and then exposed to air. It was confirmed that the Ag clusters were broken when the Ag zeolite was exposed to air for Ag zeolite-X, which complements our previous results for Ag-A.
View Article and Find Full Text PDFJ Synchrotron Radiat
September 2017
The local structure around In atoms in an m-plane InGaN film coherently grown on a freestanding m-plane GaN substrate was investigated by polarization-dependent X-ray absorption fine-structure. A step-by-step fitting procedure was proposed for the m-plane wurtzite structure. The interatomic distance for the first nearest neighbour In-N atomic pairs was almost isotropic.
View Article and Find Full Text PDFThe local structure of an amorphous tellurium (a-Te) film was investigated by extended X-ray absorption fine-structure analysis. The covalent bond length shortens and the Debye-Waller factor of the intra-chain decreases in a-Te compared with trigonal Te (t-Te). The value of the intra-chain coordination number is close to two, which is the value for t-Te, and the inter-chain interaction weakens.
View Article and Find Full Text PDFExtended x-ray absorption fine structure measurements were performed on trigonal tellurium (t-Te) and tellurium nanoparticles in very thin films. Twofold coordinated chains, much like those in t-Te, exist even in the nanoparticles, but covalent bonds or intrachain interactions are stronger than those of t-Te as shown by a shorter bond length and higher Einstein temperature. The interchain coordination number of the nanoparticles is about half that of t-Te, suggesting reduction of interchain interactions.
View Article and Find Full Text PDFChanges in the electronic structure of olivine Li(1-x)CoPO(4), 4.8 V positive electrode material for lithium ion batteries, were investigated using the X-ray absorption spectroscopy (XAS) technique. The threshold energy in the Co K-edge increased with electrochemical Li removal, indicating the oxidation of cobalt ions due to charge compensation.
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