Local Environments of Three Forms of Ba2Ycu3O6+x

Published

March 12, 1999

Author(s)

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

Abstract

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, Ba₂Ycu₃O_6+x, (x = 1,1/2, and 0). These are high Tc superconductors of T_c {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.

Citation

Physica C-Superconductivity and Its Applications

Volume

322

Pub Type

Journals

Keywords

Ba₂Ycu₃O_6+x, bonding behavior, local environments, superconductor, Wigner-Seitz atomic cell

Citation

Wong-Ng, W. , Melamud, M. and Bennett, L. (1999), Local Environments of Three Forms of Ba₂Ycu₃O_6+x, Physica C-Superconductivity and Its Applications (Accessed April 23, 2024)