抄録
High Tc superconuctors have the perovskite-related structure with copper ions on B sites, and possess large oxygen nonstoichiometry. The critical temperature is shown to have a close relationship with the oxygen nonstoichiometry. From the relationship between high temperature conductivity and oxygen nonstoichiometry, the carrier concentration and mobility are calculated and compared with those determined by other methods. The valences of copper and bismuth ions are separately determined by the chemical analysis. Contribution of bismuth ions to oxygen nonstoichiometry is shown to be more than copper ions. Detailed study on Ba (Pb1-xBix) O3 from the viewpoint of defect chemistry indicates that the oxide has large vacancy concentrations of Schottky type.
