Discussion of x-ray-absorption near-edge structure: Application to Cu in the high-T/sub c/ superconductors La/sub 1. 8/Sr/sub 0. 2/CuO/sub 4/ and YBa/sub 2/Cu/sub 3/O/sub 7/

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.1550· OSTI ID:5741545

Lytle, F W; Greegor, R B; Panson, A J

A model for interpretation of x-ray-absorption near-edge structure (XANES) in transition-metal compounds is presented based on lambda = R backscattering from nearby atoms. The model allows identification of XANES features with specific lattice distances. Reference to spectra from model compounds of simple structure allows construction of a calibration curve of ..delta..E vs R from 1.5 to 3.5 A with an accuracy of +- 0.1 A. Specific multiscattering paths were also identified in MO/sub 4/ molecules. The Cu K spectra of La/sub 1.8/Sr/sub 0.2/CuO/sub 4/ and YBa/sub 2/Cu/sub 3/O/sub 7/ were examined using the model. A unique feature in the spectra was identified with a (Cu: O) bond distance of approx.2.6 A and confirmed with analysis of the extended x-ray-absorption fine structure. This distance is evidence of antisite disorder in these compounds with 0.2--0.3 mole fraction of Cu substituting into the Y or La site. We also find evidence of simultaneous Cu/sup 2+/ and Cu/sup 3+/ valences. The structural implications of these findings are discussed.

• Research Organization: The Boeing Company, Seattle, Washington 98124
• OSTI ID: 5741545
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 37:4; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTRA
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ELECTRONIC STRUCTURE
FINE STRUCTURE
K SHELL
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
SPECTRA
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
VALENCE
X-RAY SPECTRA
YTTRIUM COMPOUNDS
YTTRIUM OXIDES