RECOVERY OF 90 K SUPERCONDUCTIVITY IN TRANSITION-METAL-DOPED Y-BA-CU-O

Most of the transition metal elements incorporated into the lattice of YBa2Cu3O7-δ are known to severely suppress the superconducting transition temperature. In this work, we show that an essentially complete recovery of the 90 K superconductivity can be achieved by partial melt processing of the material doped with Zr, Ta, Ti, Pt, Rh, and Re, which is attributed to second phase particles draining the dopant elements away from the matrix. Such a full recovery of Tc is not obtained in the case of Nb, V, Ni, Fe, Co, Pd, and Ru. The results are of technological interest in view of the need for nonpoisonous, high melting point substrate, clad or core materials desirable for melt processing of Y-Ba-Cu-O.