Dependence of critical temperature and critical current of oriented Bi₂Sr₂CaCu₂O_{8+ delta}thick films on the oxygen content

Abstract

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 (Tc) 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 (Jc) of Bi-2212/Ag melt-solidified thick films were also studied.