DEPENDENCE OF CRITICAL-TEMPERATURE AND CRITICAL CURRENT OF ORIENTED BI2SR2CACU2O8+DELTA THICK-FILM ON THE OXYGEN-CONTENT

Thermogravimetric measurement of Bi2Sr2CaCu2O8+delta was carried out as functions of temperature and partial pressure of oxygen (PO2). Dependencies of thermodynamic quantities, lattice constant and critical temperature (T(c)) on oxygen nonstoichiometry, delta, show anomalous behaviors at the same delta of 0.235. Furthermore, Bi2Sr2CaCu2O8+delta phase is found to decompose to Bi-Sr-Ca-O, Bi2Sr2CuOy and other phases at low temperature under high PO2. Effects of oxygen nonstoichiometry and the phase decomposition on critical current density (J(c)) of Bi-2212/Ag melt-solidified thick films were also studied.