SUPERCONDUCTIVITY AND ORDERING OF PR IN CALA1-XPRXBACU3O7 COMPOUND

We present the results of superconductivity, normal state magnetism, h eat capacity and neutron diffraction of the La-site Pr substituted CaL a1-xPrxBaCu3O7 system. The T-c vs x behaviour of this system appears t o be different than that predicted for orthorhombic La1-xPrxBaCaCu3O7 system. Normal state de magnetic measurements done in an applied field of 5kOe show a Curie-Weiss behaviour in terms of the paramagnetic mom ent of Pr. The effective paramagnetic moment of Pr appears to be the i ntermediate between that of the free Pr3+/Pr4+ known moments. For the non superconducting samples, i.e., for x=0.70 and 1.0, we observed an antiferromagnetic ordering temperature T-N Of nearly 4K for the former and 8K for the later fi om our de magnetic and heat capacity measurem ents. The X-ray and neutron diffraction result show that Pr substitute s isostructurally until x=1.0 in CaLa1-xPrxBaCu3O7 system with a few s mall intensity lines of unreacted BaCuO2 and CaCuO2. The lower T-N of 8K for PrBaCaCu3O7 than the known 17K for PrBa2Cu3O7 is presumably due to the intermixing of Pr and Ba site in the former compound.