Interfaces between solution-derived LiMn₂O₄ thin films and MgO and Au/MgO substrates

Spinel LiMn₂O₄ thin films have been prepared on MgO(110) and Au/MgO(110) substrates by a chemical solution deposition method. The interfaces between film and substrate were characterized by means of high-resolution transmission electron microscopy (HREM) as well as x-ray diffraction. Cross-sectional HREM observation revealed that LiMn₂O₄ films grew epitaxially on the MgO(110) and Au/MgO(110) substrates. In the LiMn₂O₄/MgO system, misfit dislocations formed to accommodate the lattice strain at the LiMn₂O₄/MgO interface. In the LiMn₂O₄/Au/MgO system, Au grew epitaxially on the MgO substrate with its surface facetted along {111} planes, probably because the surface energy of this plane is relatively low. The formation of these facets is considered to have a favorable effect on the growth of {111} planes of LiMn₂O₄ when deposited on the Au film.