Electronic Structure of Oxide Superconductors

The calculated band properties of the cuprate and bismuthate high-T sub c superconductors provide valuable insight regarding the chemistry and doping mechanisms that are operative in these compounds. In particular, these results distinguish elemental constituents that are electronically active from those which are not and suggest how substitutional doping can reduce below half the filing of the sigma -antibonding band (or bands) that are common to these materials. Despite limitations in treating electron- correlation effects, the results of such calculations on the Tl-Ba-Ca-Cu- O, Pb-Sr-Y-Cu-O, and Bi-Sr-Ca-Cu-O systems illustrate the subtle variations that can occur within the cuprate family of superconductors.