Microstructure of Ag/BaTiO3 films grown on MgO(100) substrate under external electric field.

By applying an electric field parallel to the substrate surface, highly ordered Ag nanoparticles were homogeneously embedded in BaTiO3 (BTO) films grown on a MgO(100) substrate. Transmission electron microscopy studies show that the BTO film is [100]-oriented. The general crystallographic orientation relationships between the composite film and MgO substrate are [100]BTO//[100]Ag//[100]MgO and (010)BTO//(010)Ag//(010)MgO. However, in films grown without an external electric field, Ag particles grow with random orientations and the BTO matrix is polycrystalline. Thus, electric fields are thought to meliorate the quality of the films by changing the growth orientation. In addition, the BTO matrix and Ag particles were found to be multiply twinned from studies on cross-sectional specimens. The contribution is discussed of Ag particles with ordered growth orientation and the large amount of BTO microtwins with higher dielectric constant to the improved optical properties of the as-prepared composite films. [ABSTRACT FROM AUTHOR]