The structure of the interface between BaTiO3 thin films and MgO substrates

The interface structure and interfacial defects in BaTiO3 films deposited by laser ablation on MgO (001) substrates were investigated by means of high-resolution transmission electron microscopy. Two types of structure for the (001) interface, a TiO2 plane or a BaO plane of BaTiO3 facing a MgO plane, were observed. The structure of TiO2/MgO was adopted by the main part of the interface. The occurrence of the BaO/MgO structure was found to be related to the interfacial steps with a height of n - 1/2 (n = 1,2,3,...) unit cells. The positions of the individual atomic species in the interfacial planes were clarified by investigation of both [100] and [110] images combined with image simulation. Based on lattice images along the two directions, the configuration and the Burgers vectors of interfacial dislocations were determined. The coexistence of different types of interface structure and dislocations was discussed on the basis of geometrical models of the interface structure and film growth. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.