저 순도 BaCO₃ 분말을 사용한 YBa₂Cu₃O7-y 초전도체의 합성

Abstract

YBa₂Cu₃O7-y (123) powders were synthesized by the solid state reaction method using two diferentpurity BaCO₃ powders (9.75% and 99.7% purity) and Y₂O₃ (99.9%) and CuO (99.9%) powders. The effect ofBaCO₃ purity on the formation of a 123 phase and the superconducting properties were investigated. The mixturesof raw powders were calcined at temperature ranges of 800℃-880℃ in air and finally made into a single grainsamples by a melt procesing with top seeding. It was found that a 123 phase was wel formed at temperatureabove 870℃, but the purity effect on the 123 formation was negligible. The single-grain 123 samples preparedfrom the different BaCO₃ powders showed the same Tc value of 90.5 K and similar Jc values about 104 A/cm2 at 0T and 77 K, and 103 A/cm2 at 2 T and 7 K. This result indicates that the low purity, cheap price BaCO₃ powdercan be used as a raw material for the fabrication of single-grain, high-Jc superconducting levitator.