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

Abstract

High T c superconductors, YBa 2 (Ag x Cu 1- x ) 3 O 9- 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 x <0.4, expecially YBa 2 (Ag 0.1 Cu 0.9 ) 3 O 9- y and YBa 2 (Ag 0.2 Cu 0.8 ) 3 O 9- 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.