Processing and Properties of Highly Dense Oxide Superconducting Ceramics Prepared by Coprecipitation Method

Abstract

Submicron-size superconducting powders Ba₂YCu₃O_7-δ(BYCO) having good homogeneity and reactivity were synthesized by an ethanol-aided coprecipitation method by oxalic acid. The obtained ceramics sintered at 1020°C had densities up to 98% of theoretical and exaggerated grain growth was observed at 1000°C and above. A prolonged annealing in flowing oxygen, for as long as 3 weeks, was needed to attain the zero resistivity critical temperature T_{c zero}=92K for the dense BYCO. A sharp superconducting transition, T_c=0.5K, was then obtained as defined by 10%-90% resistive transition.