RESISTIVE AND MAGNETIC-PROPERTIES OF Y1-XZRXBA2CU3O7-DELTA AND Y1-2XZRXEUXBA2CU3O7-DELTA SUPERCONDUCTIVE COMPOUNDS

The results of X-rays, electrical resistivities and magnetic studies performed on Y1-xZrxBa2CU3O7-delta and Y1-2xZrxEuxBa2CU3O7-delta superconducting compounds, in the temperature range 4.2-500 K and external fields up to 50 kOe are reported. The presence of zirconium decreases the superconducting transition temperatures, T(c). Below T(c), the hysteresis loops narrow when the zirconium content increases. From the magnetization curves, the critical current densities were determined. A time dependence of the magnetizations of logarithmic form was found. The flux-pinning energy was estimated to be U congruent-to 0.03 eV. Above the transition temperatures, Y1-xZrxBa2CU3O7-delta samples show a Pauli-type paramagnetism, while Y1-2xZrxEuxBa2CU3O7-delta Compounds have, in addition, temperature-dependent contributions to the magnetic susceptibilities. The effective europium moments are approximately 3.40 muB suggesting that the ion is in ( + 3) valence state.