Microstructure of RE2O3 layers on cube textured Ni substrates

Abstract

We investigated the structure and alignment of epitaxial Y2O3 and Gd2O3 films on cube textured Ni(001) substrates and used the findings to develop a general interpretation of the morphology of RE,03 films (RE = Y or a rare earth element) on cube textured nickel and nickel-based alloys. The [10 0] axis of RE2O3 oxides mostly prefers aligning to the Ni[0 0 1] axis, while the [0 0 1] axis is aligned with the Ni[0 0 1] axis. This (2root2 x 2root2)R45degrees extended domain matching (EDM) seems to be favored by a high coincidence site density (CSD) with the Ni(0 0 1) surface atoms, in spite of the existence of large lattice mismatches to Ni(0 0 1). Meanwhile a 3 x 3 EDM is not favored on Ni(O 0 1), in spite of the relatively small lattice mismatch to Ni(O 0 1), because of the existence of a low CSD. The broad mosaic distributions of RE2O3(0 0 1) grains (6-9degrees full-width at half-maximum) indicate that RE,03 layers prefer growing along the Ni(O 0 1) planes rather than along the Ni surface, a condition presumably induced by the favorable energetics for EDM. (C) 2002 Elsevier Science B.V. All rights reserved.