Epitaxial Stabilization of Oxides in Thin Films

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.