SUPERCONDUCTIVITY AND MAGNETIC-ORDERING OF PR IN CALA1-XPRXBACU3O7 SYSTEM

We present the results of superconductivity, normal state magnetic sus ceptibility and heat capacity measurements on the tetragonal CaLa1-xPr xBaCu3O7 compound. Ac susceptibility measurements show that the transi tion temperature T-c of the unsubstituted sample decreases with an inc rease in the Pr concentration. Normal state de magnetic susceptibility measurements performed in an applied field of 0.5 T show a Curie-Weis s behaviour in terms of the paramagnetic moment of Pr. The effective p aramagnetic moment of Pr appears to be intermediate between those of t he free Pr3+ and Pr4+ ions. For the nonsuperconducting samples i.e., x = 0.70 and 1.0, we observe an antiferromagnetic ordering temperature T-N of nearly 4 K and 8 K respectively. The X-ray diffraction results show that the CaPrBaCu3O7 compound is free from other phases, having a minor (less than 8%, in terms of peak intensity) impurity phase. The lower T-N (8 K) of PrBaCaCu3O7 as compared to the known antiferromagne tic ordering temperature of 17 K for PrBa2Cu3O7 indicates a less delet erious effect of Pr in the present case.