Superconductivity Achieved at Over Liquid Nitrogen Temperature by (Mixed Rare Earths)-Ba-Cu Oxides

Abstract

Superconducting oxides were fabricated by reaction of powders of BaCO₃, CuO and mixed rare earth (RE) carbonates at compositions expressed as (RE)₁Ba₂Cu₃O_9-y . Two types of incompletely separated raw materials of mixed rare earths, namely, heavy rare earths (HRE) and medium rare earths (MRE) were examined. The zero-resistivity critical temperatures were observed at 92.5 K for the (HRE)-Ba-Cu-O and 85.0 K for the (MRE)-Ba-Cu-O systems, respectively, both of which being well above the boiling point of liquid nitrogen.