SUPERCONDUCTIVITY IN (GD1.85-XPRXCE0.15) CUO4

We have carried out a systematic study of structural and superconducti ng characteristics of the system (Gd1.85-xPrxCe0.15)CuO4 over the enti re composition range. Superconductivity was observed for Gd0.75Pr1.10C e0.15 CuO4 at 6.5 K. Superconducting transition temperature (T-c) in t his compound was found to increase to 18 K by subjecting it to high Ar pressure annealing. However, attempts to induce superconductivity in the undoped Gd1.85Ce0.15CuO4 did not succeed. The results are explaine d as due to the increased lattice parameters of the doped compound, co nsequent upon the replacement of Gd3+-ion by larger Pr3+-ion, and the increase in the charge carrier concentration as a result of high press ure argon annealing.