The microstructure of YBa2Cu3O7-δ films and yttria stabilised zirconia buffer layers deposited on inclined hastelloy substrates

YBa2Cu3O7-delta films have been grown on polycrystalline metallic substrates using intermediate yttria stabilised zirconia (YSZ) buffer layers. The buffer layers were grown by pulsed laser deposition using the inclined substrate deposition technique, whereby the substrate is tilted so that the ablated species arrive under an oblique incidence angle. One of the consequences of the inclined geometry is the alignment of the buffer layer crystal grains within the plane of the film which enables the subsequent deposition of YBa2Cu3O7-delta films With J(c)'s of up to 10(5) A/cm(2). We present results showing that the optimum substrate inclination angle for the YSZ buffer layer deposition is around 55 degrees, and that the in-plane alignment improves linearly with film thickness. We also show transmission electron micrographs which demonstrate that grain sizes get larger and appear to be better aligned towards the buffer layer surface. We use these results to propose a mechanism by which texture occurs during inclined substrate deposition. The mechanism is based on three requirements inferred from our microstructural data: columnar growth, tilting of grains towards the incoming ablated species, and a preferred growth orientation normal to the substrate surface.