Preparation of Y123 films on REAlO 3-buffered off-cut substrates of R-plane sapphire

Abstract

An epitaxial YBa 2Cu 3O 7− x (Y123) film was prepared on a REAlO 3 (RENd)-buffered vicinal (off-cut angle: 4.5°) α-Al 2O 3( 1 ̄ 0 1 2) substrate and their crystallographic relationship was investigated. Both the NdAlO 3-buffer layer and Y123 film were obtained by a coating-pyrolysis process. The XRD θ–2 θ scanning exhibited the growth of a/ c-oriented Y123. However, XRD ω-scanning of the Y123 006 reflection showed that the c-axis oriented grains comprised two components; the intensity ratio being >2:1. The c-axis of the major component was perpendicular to the substrate surface whereas that of the minor one inclined ∼10° away from the surface normal. These results suggest that, if properly optimized, epitaxial Y123 films of which the c-axis is dominantly parallel to the substrate normal would be obtained by using the REAlO 3-buffered vicinal substrates whereas doubly tilted Y123 films would occur if instead the normal α-Al 2O 3( 1 ̄ 0 1 2) substrates without off-cut were used.