Abstract
Sr-based 123 compounds R1-xCaxSr2Cu2.7Mo0.3Oy with R = Pr, Nd, and Y are successfully stabilised by partial substitution of Mo for Cu. A tetragonal-orthorhomic-tetragonal transition is observed for R = Y and Nd, which is induced by different oxygen content in the samples. Tc of the samples is sensitive to the oxygen content other than the structure. For Pr-contained samples the resistivity decreases systematically with increasing the Ca dopant and oxygen content. The results show that the hybridisation of the conduction electrons with the 4f band of Pr in Sr-based 123 compounds is weaker than that in Ba-based 123 compounds.