Ag-clad Bi-Sr-Ca-Cu-O wires: II. Important factors in supersolidus phase studies

Abstract We studied the effect the quench rate has on the phase assemblage observed at room temperature in the Bi:Sr:Ca:Cu oxide system for Ag-clad 2:2:1:2 wire that had been quenced from above the solidus. Ag, which dissolved into the melt from the cladding, and “2201” precipitated out of the melt in samples quenched in liquid nitrogen or air due to the relatively slow quenching rate. In contrast, the quench rate in oil was rapid enough to prevent these phase from forming. In oil-quenched samples, “2201” was not observed indicating that “2201” is not a precursor phase to “2212”. These wire samples contained several minor phases that were difficult to identify in the multiphase X-ray diffraction patterns. We examined the X-ray diffraction pattern for (Sr 1− x Ca x )CuO 2 ( x =0.4), a phase found in the wire that has a wide range of solid solution and whose X-ray pattern is quite different than the end member SrCuO 2 . Identifying and indexing the diffraction peaks due to this phase were aided by the quantitative chemical data we collected on each phase present in the wire.