SYNTHESIS METHOD, CONTROL OF CATIONIC COMPOSITION AND SUPERCONDUCTINGBEHAVIOR OF ND1.85CE0.15CU1+ -DELTA-OY/

Samples of Nd1.85Ce0.15Cu1 +/- delta O-y (0.99 less than or equal to 1 +/- delta less than or equal to 1.02) were prepared by a solid-state reaction (SSR), nitrate-decemposition method (NDM) and liquid-mix meth od (LMM) and characterized by XRD, SEM, EPMA, DTA and DC magnetization . The control of Cu content, substitutional impurities and Ce homogene ity depends on the synthesis method, which modifies the microstructure and the superconducting behavior of these materials. Our results show that in Nd1.85Ce0.15Cu1 +/- deltaOy small variations of 6 strongly af fect the superconducting properties. Far 1 + delta > 1.00 the Meissner fraction and the superconducting transition are substantially improve d.