NONSTOICHIOMETRY AND DECOMPOSITION OF PR1-ZCU3OY AND COMPARISON WITH Y123, LA123 AND ND123(ZBA2)

The temperature (T) and O-2 partial pressure (p[O-2]) dependence of th e oxygen content (y) in Pr1+zBa2-zCu3Oy (Pr123) were determined over t he entire range of z and the data were represented by chemical thermod ynamic models. Comparison of the results with those published previous ly for Y123, La123 and Nd123, indicated that the La123 system was the most atypical. Thermodynamic arguments suggest the presence of Pr+4 as y approaches its maximum value. The T-z-p[O-2] dependence of high-tem perature decomposition was also determined. Resistivity, de magnetizat ion, and susceptibility measurements as low as 5 K revealed only param agnetic and semiconducting behavior.