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Abstract

A process for producing a high critical temperature bismuth strontium calcium copper oxide superconducting material. An intimate mixture is formed of two superconducting materials. The first material is bismuth strontium calcium copper oxide or (bismuth, lead) strontium calcium copper oxide, and has a bulk critical temperature below about 90K. The second material is a seeding powder of bismuth strontium calcium copper oxide or (bismuth, lead) strontium calcium copper oxide, and includes at least 20 volume percent 2223 phase. The amount of seeding material added to the mixture is selected to result in an amount of 2223 phase in the mixture of about 2-50 weight percent. The mixture is annealed in an oxidizing atmosphere at a temperature of at least about 845.degree. C. and below the melting temperature of the 2223 phase, for a time sufficient to increase the amount of 2223 phase in the mixture. In an alternate embodiment, one or both of the superconducting materials in the mixture are provided by drying, calcining, and annealing a precursor mixture of a Sr(NO.sub.3).sub.2 solution, a Ca(NO.sub.3).sub.2, solution, a Cu(NO.sub.3).sub.2 solution, a Bi.sub.2 O.sub.3 powder, and a PbO powder.

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