ELECTRONIC-STRUCTURE OF BA(SN,SB)O3 - ABSENCE OF SUPERCONDUCTIVITY

The electronic structures of BaSnO3, BaSbO3, and BaPbO3, calculated using an extended general-potential linearized augmented-plane-wave method, are reported. The electronic structures of BaSnO3 and its 6s analog BaPbO3 are found to be very different, explaining the absence of superconductivity in the Ba(Sn,Sb)O3 system. These differences are explained by a combination of the relativistic lowering of the 6s states and ion-size effects. Muffin-tin-approximation augmented-plane-wave calculations for BaSnO3 are also reported and the utility of the muffin-tin approximation for this and similar materials is discussed in terms of the differences between the two sets of calculations.