Effect of doping and substitution on the low-temperature decomposition of oxygen-nonstoichiometric Ba2YCu3O7 − δ

Effects of doping (with Ce and Pr) and substitution of Sr, Nd, Eu, and Ni for Ba and Cu on the lowtemperature (T = 200–300°C) decomposition of oxygen-nonstoichiometric Ba2YCu3O7 − δ have been studied. Both the doping and partial substitution for any of the principal components was found to increase the stability of the 123 compounds with respect to the decomposition into oxygen-depleted and oxygen-rich phases. Both doping and substitution to a level of ∼2% lead to a narrowing of the immisibility dome and a decrease in the critical temperature. In the first place, the decomposition is suppressed in the bulk of grains. To increase the stability of near-boundary regions of grains, a high degree (∼20 at %) of substitution is necessary.