ELECTRICAL TRANSPORT AND SUPERCONDUCTIVITY IN A PRBA2CU3O7-GDBA2CU3O7 COMPOSITE SYSTEM

Composite samples of PrBa2Cu3O7-GdBa2Cu3O7 have been fabricated with the nominal GdBa2Cu3O7 volume fraction-phi ranging from 0.00 to 1.00. Resistivity and magnetization measurements performed on the samples are interpreted in terms of sample structure composed of GdBa2Cu3O7 and PrBa2Cu3O7 grains embedded in a Gd1-xPrxBa2Cu3O7 matrix. The Pr concentration x as a function of phi is established by inferring it from the superconducting transition temperature T(c). In particular, both the resistivities and magnetizations show drastic changes when phi exceeds about 0.6. This is the value of phi at which x first exceeds a critical value of about 0.5 and where the Gd1-xPrxBa2Cu3O7 matrix first superconducts. The Gd1-xPrxBa2Cu3O7 phase is presumably formed during the high temperature (900-degrees-C) firing process which results in mutual substitution between the Gd and Pr atoms.