High-Tc Superconductors Prepared by Oxidation of Vapor-Quenched Amorphous Alloy Films in Ba-Y-Cu and Ba-Yb-Cu Systems

Amorphous Ba 1 Y 2 Cu 5 and Ba 2 Yb 1 Cu 6 alloy films were obtained by rf sputtering. The oxidization treatment by annealing of the alloy films in the range of 1173 to 1223 K in an oxygen flowing atmosphere gave rise to the formation of Ba 1 Y 2 Cu 5 O y and Ba 2 Yb 1 Cu 6 O y oxide films. The Ba 1 Y 2 Cu 5 O y and Ba 2 Yb 1 Cu 6 O y films consisted mainly of an orthorhombic phase and exhibited high- T c superconductivity with onset at 91 and 86 K and zero resistance at 75 and 82 K, respectively.