CONTROLLED ROOM-TEMPERATURE REDUCTION OF YBA2CU3O7-X - A SYNTHETIC ROUTE TO METASTABLE SUPERCONDUCTING PHASES

The oxygen content of YBa2Cu3O7-x can be reduced electrochemically in a non-aqueous electrolyte at room temperature. The products are characterized by x-ray powder diffraction, magnetic susceptibility and electrical conductivity. The transition to the superconducting state is broadened upon reduction. Subsequent annealing of the reduced samples yields materials with distinct 90, 60 and 20 K transitions. These results indicate that the oxygen content is the primary factor in controlling Tc.