MAGNETIC AND MICROWAVE PROPERTIES OF SM1-XBA2CU3+XO7-DELTA SUPERCONDUCTORS AT 4.2-K PREPARED BY AN ORGANIC CARBONATE COPRECIPITATION ROUTE

Abstract

Samples of Sm1Ba2Cu3O7-delta and Sm0.95Ba2Cu3.05O7-delta are prepared by a coprecipitation technique using organic carbonates in the presence of stable polymers. The electrical, magnetic, and microwave measurements have been carried out to characterize the materials. Both normal (Sm1Ba2Cu3O7-delta) and copper-rich (Sm0.95Ba2Cu3.05O7-delta) samples showed sharp superconducting transitions at 94 K. Lower and upper critical fields of the samples are estimated from magnetization measurements. The critical magnetization current density (J(mc)) and pinning force density (F(p)) of the samples are obtained from the magnetization hysteresis loop at 4.2 K for fields up to 5 T. Superconducting parameters (H(c)(O), K(GL), lambda, xi) are obtained by using the values of lower and upper critical magnetic fields. Microwave-induced d.c. voltage measurements indicated a smaller number of weak links for copper-rich samples. The enhancement of critical current density and the reduction of total number of weak links for copper-rich samples may be due to the increase in hole concentration caused by the partial replacement of Sm by Cu.