Enhanced T c and Strong Flux Pinning in Melt-Processed NdBa 2 Cu 3 O y Superconductors

The effects of various oxygen partial pressures ( P O2 ) during melt processing on the superconducting properties of fabricated NdBa 2 Cu 3 O y (Nd123) superconductors have been systematically investigated. Unlike in air or O 2 , samples melt-processed in reduced oxygen atmospheres exhibited unprecedentedly high T c 's of 95–96 K with a sharp superconducting transition. Especially, for a sample melt-processed in 0.1% O 2 in Ar, the magnetization hysteresis ( M-H ) loop was kept open up to 7 T at 77 K and for the field parallel to the c -axis of the sample ( H // c ), implying that very effective flux pinning can be achieved in high magnetic fields.