Influence of Oxygen Content on the Superconductivity of Bi-Based Oxides Homologous to 2212 Phase

Abstract

Thermal desorption of oxygen and its relevance to superconductivity were examined for a series of oxides Bi 2 Sr 2- x Ca 1+ x Cu 2 O y ( x =0, 0.25, 0.5, 0.8 and 1.0) isostructural to the 2212 phase. The total oxygen desorbed up to 600°C amounted to 2∼3×10 -5 mol/g for each oxide. T c was constant at about 80 K for all the as-prepared oxides but T c decreased linearly with x from 97 K ( x =0) to 67 K ( x =1.0) for the oxygen-desorbed oxides. The total oxygen contents ( y ) were determined and correlated with T c , which increased for x =0 and 0.25, whereas it went through a maximum at about y =8.15 for x =0.8.