SUPERCONDUCTIVITY IN REDUCED AND THEN REOXIDIZED ND1.05BA1.59(CU1-XFEX)(3)O7-DELTA

The system Nd1.05Ba1.95(Cu1-xFex)(3)O7-delta (NdFe-123) was studied. S ubstitution of Fe for Cu suppresses superconducting transition tempera ture T-c more rapidly in the NdFe-123 system than in the comparable YB a2(Cu1-xFex) (YFe-123) system. Samples reduced in argon and then reoxi dized in oxygen at 400 degrees C show considerable increases in T-c. H owever, the T-c of these reoxidized samples still fall below those of similar YFe-123, Microstructural investigation by electron microscopy, structure from X-ray diffraction and their relationships to supercond uctivity are developed. Possible mechanisms for the T-c variations are discussed. (C) 1998 Elsevier Science B.V.