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Local Environments of Three Forms of Ba2Ycu3O6+x



Winnie K. Wong-Ng, M Melamud, Lawrence H. Bennett


The Wigner-Seitz local atomic cell construction procedure, provides a topological means for comparing series of related structures in terms of the number and type of nearest neighbors. We used this construction to further our understanding of the chemical bonding environment (and hence, the superconducting properties) in three structurally related materials, Ba2Ycu3O6+x, (x = 1,1/2, and 0). These are high Tc superconductors of Tc {approximately equal to} 92K, 56K, and a non-superconductor, respectively. The local environment around Y is found to be similar in all three compounds and the topology around Ba is generally similar to that in the ideal perovskite. The Cu sites in the Cu-O plane in all three materials show similar anisotropic bonding behavior. Significant results are (I) that Ba contributes to the bonding with Cu sites, and (ii) the most noticeable difference in the local environment in these compounds is around the Cu sites in the Cu-O chains. We propose a modified charge-transfer model, involving the Cu-O chains, planes and Ba as an electronic unit, to correlate structure with the observed superconducting properties. The bonding behavior of these oxides also appears to be different from the conventional metal alloy superconductors.
Physica C-Superconductivity and Its Applications


Ba<sub>2</sub>Ycu<sub>3</sub>O<sub>6+x</sub>, bonding behavior, local environments, superconductor, Wigner-Seitz atomic cell


Wong-Ng, W. , Melamud, M. and Bennett, L. (1999), Local Environments of Three Forms of Ba<sub>2</sub>Ycu<sub>3</sub>O<sub>6+x</sub>, Physica C-Superconductivity and Its Applications (Accessed July 24, 2024)


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Created March 12, 1999, Updated February 19, 2017