X-Ray Absorption Studies of La2−xSrxCuO4 and Y1−xPrxBa2Cu3O7-δ

1987 ◽  
Vol 99 ◽  
Author(s):  
E. E. Alp ◽  
G. K. Shenoy ◽  
L. Soderholm ◽  
G. L. Goodman ◽  
D. G. Hinks ◽  
...  
Keyword(s):  
Rare Earth ◽  
Cross Section ◽  
Atomic Clusters ◽  
Oxide Superconductors ◽  
Absorption Cross ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Studies ◽  
High Transition ◽  
X Ray Absorption

ABSTRACTThe question of valence of Cu and rare-earth atoms in the newly discovered oxide superconductors with high transition temperatures is crucial to the understanding of their electronic structure. We have measured the X-Ray Absorption Near Edge Structure (XANES) of Cu K transition and Pr Ljjj transition to obtain information on the valence of Cu, and Pr in La2−xSrxCuO4 and Y1−xPrxBa2Cu3O7-δ. We will present the experimental results, compare them with calculations of absorption cross-section for model atomic clusters, and discuss the valence of Cu as a function of oxygen concentration.

scholarly journals Anisotropy of X-ray Absorption Cross Section in CeCoGe3 Single Crystal

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 544
Author(s):  
Andrei Rogalev ◽  
Fabrice Wilhelm ◽  
Elena Ovchinnikova ◽  
Aydar Enikeev ◽  
Roman Bakonin ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Linear Dichroism ◽  
X Rays ◽  
Absorption Cross ◽  
X Ray ◽  
Measured Absorption ◽  
Linearly Polarized ◽  
X Ray Absorption ◽  
Absorption Edges

Absorption spectra of two orthogonal linearly polarized x-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the “average” anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions.

Fluorescence Extended X-Ray Absorption Fine Structure Study on Local Structures of Rare-Earth-Doped InGaGdN

2016 ◽  
Vol 1133 ◽  
pp. 429-433
Author(s):  
Siti Nooraya Mohd Tawil ◽  
Shuichi Emura ◽  
Daivasigamani Krishnamurthy ◽  
Hajime Asahi
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Nearest Neighbor ◽  
Structure Study ◽  
Edge Structure ◽  
X Ray ◽  
Local Structures ◽  
Absorption Fine ◽  
X Ray Absorption

Local structures around gadolinium atoms in rare-earth (RE)-doped InGaGdN thin films were studied by means of fluorescence extended X-ray absorption fine structure (EXAFS) measured at the Gd LIII-edges. The samples were doped with Gd in-situ during growth by plasma-assisted molecular beam epitaxy (PAMBE). Gd LIII-edge EXAFS signal from the GaGdN, GdN and Gd foil were also measured as reference. The X-ray absorption near edge structure (XANES) spectra around Gd LIII absorption edge of InGaGdN samples observed at room temperature indicated the enhancement of intensities with the increase of Gd composition. Further EXAFS analysis inferred that the Gd atoms in InGaN were surrounded by similar atomic shells as in the case of GaGdN with the evidence indicating majority of Gd atoms substituted into Ga sites of InGaGdN. A slight elongation of bond length for the 2nd nearest-neighbor (Gd–Ga) of sample with higher Gd concentration was also observed.

Multiple Scattering Calculations Applied to XAS: A Structure and Electronic Sensitive Tool

1991 ◽  
Vol 253 ◽  
Author(s):  
Philippe Sainctavit ◽  
J. Petiau
Keyword(s):  
Multiple Scattering ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Scattering Theory ◽  
Spectral Features ◽  
Absorption Cross ◽  
Multiple Scattering Theory ◽  
X Ray ◽  
Sensitive Tool ◽  
X Ray Absorption

ABSTRACTWe present an application of multiple scattering theory with “muffin-tin” potentials to the calculation of X-ray absorption cross section. We have measured and calculated the K-edge spectra of atoms in compounds with zincblende structure : SiC, ZnS. We show that some spectral features can be precisely related to the local environnement around the absorbing atom.

scholarly journals Determination of the host phase of rare earth elements in natural carbonate using X-ray absorption near-edge structure

2009 ◽  
Vol 43 (3) ◽  
pp. 143-149 ◽  
Author(s):  
KAZUYA TANAKA ◽  
YOSHIO TAKAHASHI ◽  
HIROSHI SHIMIZU
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

Polarized X-Ray Absorption Studies of Oxide Superconductors

1988 ◽  
Vol 143 ◽  
Author(s):  
E. Ercan Alp ◽  
S. M. Mini ◽  
M. Ramanathan ◽  
B. W. Veal ◽  
L. Soderholm ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Oxide Superconductors ◽  
Oxygen Doping ◽  
X Ray ◽  
Cluster Calculations ◽  
Absorption Studies ◽  
X Ray Absorption ◽  
Absorption Edges

AbstractPolarized X-ray absorption studies have been carried out at the Cu K-edge to study the effect of Sr doping in La2CuO4 and oxygen doping in YBa2Cu3O6+x. These measurements help to elucidate the transitions giving rise to the absorption edges. We offer an explanation of the polarization shifts of features in terms of the results of our embedded cluster calculations of electronic structure.

scholarly journals Structural Change Analysis of Cerianite in Weathered Residual Rare Earth Ore by Mechanochemical Reduction Using X-ray Absorption Fine Structure

2019 ◽  
Author(s):  
Tatsuya Kato ◽  
Yuki Tsunazawa ◽  
Wenying Liu ◽  
Chiharu Tokoro
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Structural Change ◽  
Oxygen Vacancy ◽  
Structural Changes ◽  
Mechanochemical Reaction ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Prolonged high-intensity grinding can modify the crystal structure of solid substances and/or induce chemical reaction, which is referred to as mechanochemical reaction. Such reactions can exert positive influences on hydrometallurgical processes, therefore, many researchers have applied mechanochemical reactions for metals dissolution from minerals. The mechanism of mechanochemical reaction has been investigated using solid analyses and simulations. Structural changes caused by mechanochemical reaction are not yet sufficiently clarified because the ground samples are amorphous. The objective of this study was to analyze structural changes of cerianite in weathered residual rare earth ore by mechanochemical reduction. Structural change was analyzed by x-ray absorption near-edge structure and extended x-ray absorption fine structure analysis at the cerium LIII- and K-edges. These analyses revealed that the structural change of cerianite in this ore induced by mechanochemical reduction involved oxygen vacancy production. The process of the oxygen vacancy formation was closely coupled with the quantum effect of localization–delocalization of the 4f electron of cerium.

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