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 BaCu 3 O 4, NdMn 7 O 12, RNiO 3, and unusual polymorphous forms of BaRuO 3, RMnO 3, TiO 2, and Mn 3 O 4 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.