Composition Dependence of Superconductivity in Y-Ba-(Ag, Co)-O System

Abstract
High T c superconductors, YBa2(Ag x Cu1-x )3O9-y with composition of 0≦x≦0.6 were prepared by a ceramic technique, and the compositional change of T c was examined. Samples with nominal compositions of x2(Ag0.1Cu0.9)3O9-y and YBa2(Ag0.2Cu0.8)3O9-y , show sharp superconducting transitions with widths as narrow as about 1 K or less. The superconductivity is discussed in relation to the results of X-ray diffraction study.