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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The formation of previously unknown hexagonal modifications of orthoferrites RFeO3 (R = Eu−Lu) was observed on ZrO2(Y2O3) (111) substrates at 900 °C. XRD and HREM studies reveal epitaxial growth of the hexagonal film. The structure of the hexagonal RFeO3 was assigned to the ferroelectric space group P63 cm. The typical structural defects in the hexagonal RMnO3 films on ZrO2(Y2O3) (111) are described. Parallel deposition on perovskite substrates results in the stable perovskite phase. The epitaxial stabilization concept successfully explains the experimental results.