Superconducting tapes using ISD buffer layers produced by evaporation of MgO or reactive evaporation of magnesium

To avoid large angle grain boundaries in YBa₂Cu₃O₇ (YBCO) thin films, biaxially textured buffer layers were grown by inclined substrate deposition. We use MgO as buffer layer material, which can be grown at rates up to 300 nm/min using either e-beam evaporation of MgO or reactive thermal evaporation of magnesium. Employed substrates were Hastelloy C276 or stainless steel. Epitaxial YBCO was grown on these buffer layers by thermal co-evaporation. We reached YBCO in plane texture of 7° FWHM and critical currents along tape direction of 84 A on tapes with 8 mm width and 1.8 μm YBCO thickness which means a current density of 0.58 MA/cm².