Phase stability of erbium barium cuprate, ErBa 2Cu 3O 7− x and ytterbium barium cuprate, YbBa 2Cu 3O 7− x

Abstract

A thermodynamic study of the phase stability of rare earth barium cuprates, REBa 2Cu 3O 7− x or REBCO (RE=rare earth––Er, Yb) has been carried out over the temperature range 750–960 °C and pO 2 range 1.0×10 −4–2.1×10 −1 atm using a coulometric titration technique. The peritectic temperature, T p, at a given pO 2, decreases with decreasing rare earth ion size, with a lowering of T p by up to 100±5 °C for YbBCO compared to YBCO and 55±5 °C for YbBCO compared to ErBCO. The minimum peritectic temperature, T p-min, is 860±10 °C (under reducing conditions), and is independent of the rare earth ion.