Compositional homogeneity in processing precursor powders to the Ba2YCu3O7−x high Tc superconductor

Abstract

We have used scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) to study compositional homogeneity at several stages in the processing of powders to the Ba₂YCu₃O_x high T_c superconductor. We investigated the effects of solution pH and ionic concentration in the precipitation preparation of mixed hydroxycarbonates of Ba, Y, and Cu as precursor to the Ba₂YCu₃O_7−x high T_c superconductor. Our results show that both powder homogeneity and particle morphology are strongly dependent on these parameters. Additionally, studies of the compacted powders by EDS mapping at successive stages of processing show the development of phase inhomogeneities even in homogeneous starting powders.