HREM study of epitaxially stabilized hexagonal rare earth manganites

The formation of the high-temperature hexagonal modification of DyMnO3 and nonexisting as bulk hexagonal EuMnO3, GdMnO3, and SmMnO3 was observed on ZrO2(Y2O3) (111) substrates at 900 degreesC due to epitaxial stabilization. HREM study reveals epitaxial growth of the hexagonal film of limited thickness depending on the nature of the rare earth cation. For thickness exceeding critical, the oriented stable perovskite form grows semicoherently on the hexagonal phase. The interface of two polymorphs is not abrupt and involves the formation of the transition zone with the characteristic pyramid-like shapes on the top of the hexagonal layer. The typical structural defects in the hexagonal RMnO3 films are described.