Electron-Cyclotron-Resonance Microwave Plasma Oxidation of Er1Ba2Cu3Oy Superconductive Ceramics

Abstract

An electron-cyclotron-resonance (ECR) microwave plasma was introduced to the forced oxidation of high-T _c Er₁Ba₂Cu₃O _y superconducting ceramics in oxygen pressure as low as 0.9 Pa. The negative bias (-40 V) application to the specimen greatly helped the progress of the plasma oxidation as compared with the positive bias (+30 V) one. The accumulation of the oxygen atoms ionized positively is thought to be responsible for the observed bias effect. A higher substance temperature and input microwave power also enhanced the plasma oxidation. A 30-minute oxidation was sufficient to obtain the superconductivity with T _c≧92 K.