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.