Solid solution compositions of Pb3(Sr, Ca)5CuOy and refinement with the rietveld method

In the last years several new phases have been investigated in the (Bi,Pb)-Sr-Ca-Cu-O-System. Some of these phases are stable in precursors which are used to produce 2223-BPSCCO-HTSC tapes. They are playing an important role for the formation of the 110 K 2223-phase. One of these phases was defined as the 3321-BPSCCO phase. These phase was determined with the composition Pbs(3-x)Bi(x)Sr(3)Ca(2)CuO(y) with x = 0-0.5. Several solid solutions with different Ca/Sr ratios were synthesized and refined with the Rietveld method using a structure model from the isotype compound Pb3Sr5CuO12. These investigations are clearing the actually Ca/Sr ratio of this phase in the precursors. Getting exact information about the solid solution composition of each phase is another step for the quantitative phase analysis of the precursor powders, which will help understanding the formation of the BPSCCO-2223 superconductor. These investigations are aiming to a quantification routine for the 2223-HTSC precursors by the Rietveld method and establishing a quality control method for the powder processing of these products.