Synthesis of Ceramics from Solutions: Functionally Graded Composites, NanoComposites and Single Crystal Thin Films. Epitaxial Growth and Structure of Highly Mismatched Oxide Films with Rock-Salt Structure on MgO.

CaO thin films were grown on 001 MgO single crystal substrates by a chemical solution deposition method to study the influence of a relatively high lattice mismatch 14 on the epitaxial growth. In order to minimize an influence of a different crystal structure and chemistry between film and substrate, film and substrate were chosen to have the same structure NaCl and a similar chemistry. The films were heat treated until they broke up into single crystal islands on the MgO substrate. X-ray pole figure analysis and TEM observations of the CaO-films showed that most of the grains had a single out-of-plane orientation 111CaO parallel lines 001MgO, corresponding to two non-redundant, symmetry related in-plane variants 110111CaO parallel lines 110001MgO and 110111CaO parallel lines 110001MgO. A sigma 7 sigma 8 Near Coincidence Site Lattice NCSL model could be constructed for the interface, that suggests good lattice and charge matching for the observed orientation relations. The mechanisms and energetics leading to the experimentally observed orientation relations are discussed.