Valence and Coordination of Cu Ions in High Tc Superconductor BaxY1-xCuO3-y
- 1 May 1987
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 26 (5A) , L638
- https://doi.org/10.1143/jjap.26.l638
Abstract
Cu K near-edge and extended X-ray absorption fine structure (EXAFS) have been measured for 90 K superconductor BaxY1-xCuO3-y with x=0.6. The Fourier analysis of EXAFS shows that Cu ions are coordinated with basal plane oxygens having the average Cu-O distance of 1.97 Å. Determined average oxygen coordination number of ca. 4.8 suggests the presence of axial oxygens with a similar Cu-O distance. The near-edge spectra provide an evidence for the mixed valence character of Cu ions in BaxY1-xCuO3-y between predominantly divalent states and trivalent states. The strong electron-phonon interaction may be further enhanced by a charge-coupled motion of oxygens induced by the Cu valence fluctuation.Keywords
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