A survey of recent experimental results is given, presenting the growth of oxide epitaxial thin films in P−T−x conditions, which are far from those necessary for the existence of corresponding phases in a bulk state. The unstable in bulk BaCu3O4, NdMn7O12, RNiO3, and unusual polymorphous forms of BaRuO3, RMnO3, TiO2, and Mn3O4 are some examples. The stabilizing effect is observed only if epitaxial growth is induced. A rich variety of the effect observations are demonstrated to be of a thermodynamic origin, rather than of a kinetic one. Epitaxial stabilization is shown to be the result of the low energy of coherent interfaces formed due to epitaxy.

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We have succeeded in the preparation of thin films of rare-earth nickelates RNiO3 (R=Pr, Nd, Sm, and Gd) under reduced oxygen pressure <0.02 bar by metalorganic chemical-vapor deposition owing to their epitaxial stabilization on perovskite substrates. The film–substrate lattice mismatch is critical for the epitaxial stabilization of RNiO3 phases. Increase of the lattice mismatch or film thickness results in the deposition of rare-earth oxides and NiO instead of RNiO3. The epitaxial films of nickelates were strained and consisted of 90° domains with the orthorhombic Pnma structure. The transport properties of the strained films on LaAlO3 were similar to those of the bulk material of the same composition under applied pressure of 9 kbar but they were different from the properties of the bulk material under ambient pressure. The result implies that transport properties of RNiO3 films with sharp metal-to-insulator transition can be effectively tuned by the control of the lattice strain.

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The methods of synthesis of new oxide compounds and The methods of synthesis of new oxide compounds and thin-film materials based on the use of heteroepitaxy are consid-thin-film materials based on the use of heteroepitaxy are considered. The thermodynamic model and the theory of the epitaxial ered. The thermodynamic model and the theory of the epitaxial stabilisation phenomenon are outlined, the role of thermody-stabilisation phenomenon are outlined, the role of thermodynamic and structure-geometric factors determining the possibility namic and structure-geometric factors determining the possibility of epitaxial stabilisation of unstable phases is interpreted. The use of epitaxial stabilisation of unstable phases is interpreted. The use of epitaxial stabilisation for the design of heterostructures with of epitaxial stabilisation for the design of heterostructures with specific electric properties is demonstrated. The characteristic specific electric properties is demonstrated. The characteristic features of the structural relations between the film and substrate features of the structural relations between the film and substrate materials, resulting in the formation of thin films with different materials, resulting in the formation of thin films with different numbers of variants, are discussed. The bibliography includes 128 numbers of variants, are discussed. The bibliography includes 128 references references. .