Precursor preparation by a modified oxalate coprecipitation and its suitability for manufacturing Bi(Pb)SrCaCuO-conductors

Two of the most promising methods for the preparation of conductors for energy applications of HTSC are the ''Powder-in-tube-method'' and the Doctor-Blade process using Ag as substrate material. The authors compared the suitability of precalcined B(PSCCO) precursor powders made by different routes, especially by a modified coprecipitation of oxalates. The material was tested in wire-form and as coated Ag-substrates. Phase purity, stoichiometry, homogeneity, reactivity, C-content and particle sizes were investigated by XRD, SEM, EDX, ICP-AES, AC-susceptibility and particle-size measurements. The precursor powders prepared by the modified coprecipitation exhibit improved properties in comparison to conventional routes. For ''Powder-in-tube'' tapes the precursor could be converted in monofilamentary samples in less than 100h with only one intermediate pressing step to jc-values up to 1. 5 * 104 A/cm2 (0T/77K) at this time. In the case of the Doctor Blade-process large surfaces could be homogeneously coated with a thickness of 15 μm and reacted to dense and highly textured microstructure. Optimized jc-values are up to 1.0 * 101 A/cm2 (0T/77K)