SUPERCONDUCTING PROPERTIES IN OXYGEN-DEFICIENT BA1-XKXBIO3-DELTA

Ceramic samples of Ba1-xKxBiO3-delta were prepared with parameters of composition x and oxygen content 3-delta, and superconducting properties were measured. A contour mag of T-c was constructed on a diagram of composition x and oxygen content 3-delta. A single peak of T-c is found to be located at 3-delta congruent to 3 and x congruent to 0.38. The line along x congruent to 0.38 which forms a ridge in the T-c-contour map seems to correspond to a phase boundary at low temperatures between the orthorhombic and cubic crystal structures. This result exhibits that the superconductivity also occurs in the orthorhmbic structure.