SUPPRESSION OF SUPERCONDUCTIVITY IN THE ER1-XPRXBA2CU3O7-DELTA SYSTEM

Measurements of electrical resistivity, X-ray diffraction patterns, ma gnetic susceptibility and thermoelectric power of the Er1-xPrxBa2CuO7- delta system have been made. The superconducting transition temperatur e was found to decrease monotonically with praseodymium concentration, x. From the susceptibility data, it was determined that the valence o f praseodymium lies between + 3 and + 4. The thermoelectric power was found to increase with x, and the slopes of dS/dT were negative except for the case x = 0. The . tendency of the thermopower to change with increasing praseodymium concentration has been qualitatively explained using the theory for strongly correlated systems.