Preparation of Superconducting Y–Ba–Cu–O and Bi–Pb–Sr–Ca–Cu–O Compounds by Chelating Method

Abstract

Superconducting Y–Ba–Cu–O (YBCO) and Bi–Pb–Sr–Ca–Cu–O (BPSCCO) compounds were prepared by a chelating method with various chelating agents, such as nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA) and ethylenediaminetetraacetic acid (EDTA). Above 600°C, the precursors YBCO and BPSCCO turned into a mixture of metal oxides and BaCO₃, which finally transformed into the almost single phase of YBCO at 850∼930°C and into the high-T _c phase of BPSCCO at 840°C. The critical current densities of YBCO and BPSCCO in blocks of 1*4*15 mm³ were estimated to be as high as 350 and 500 A/cm² at 77 K, respectively.