The effect of the substitution of Sm for Ba on the superconductor

Abstract

Characteristic changes occurring in superconductors on substituting Sm for Ba have been investigated. An appropriate amount of Sm substitution (, in the form of ) promoted grain growth; the grain size became larger than that in the non-substituted sample and had a maximum value at x = 0.07. Single-phase samples were obtained for . The critical temperature increased by about 1.5 K for concentrations up to x = 0.02, while it decreased rapidly beyond this amount. Samples did not show superconductivity above 15 K for . The crystal structure transformed from orthorhombic to tetragonal at x = 0.3. The average valency of the Cu and the oxygen content decreased linearly with increase of x in the ranges of and , while they both increased linearly for the range .