MICROANALYTICAL AND METALLOGRAPHIC CHARACTERIZATION OF INTERACTIONS BETWEEN YBACUO SUPERCONDUCTORS AND VARIOUS SUBSTRATES

Annealed laminates of YBa2Cu3Oy films on AgPd, SnO2 and Pt substrates were investigated by metallography, EPMA, and XDA. Thin homogeneous la yers of Ba2SnO4 and BaZrO3 (in case of a ZrO2 diffusion barrier onto o ne side of AgPd) between ceramic and SnO2 or AgPd substrates were foun d. The adjacent interface is inhomogeneous and Y free for both substra tes (for Pt two exist). The composition of their major phase could be shown to be a Ba2Cu3O5 type with Pd partitions instead for Cu (in case of ZrO2 contact), a YBa2Cu3Oy type without Y, but containing Pd (+ Ag ) (in case of AgPd contact), Ba2SnO4 precipitates and BaCuO2, CuO part icles are mixtures (SnO2 contact). Pt seems not to participate to any phase constituents; the two interfaces differ in the fine distribution of the phases concerned and therefore in the mean value of Ba, Cu, Pt concentrations.