Structural characterization of epitaxial BaTiO3 thin films grown by sputter deposition on MgO(100)

Epitaxial thin films of BaTiO3 have been prepared using radio-frequency magnetron sputter deposition on MgO(100) substrates. Various x-ray-diffraction techniques were employed to characterize the crystal structure of the films. The films were fully tetragonal and consisted of c domains. Their tetragonality has been shown to be 1.013, which is almost the same as the bulk value of BaTiO3. However, the cross-sectional transmission electron microscopic micrograph showed that a very small amount of a domains coexists forming 90° domain boundaries in the matrix of c domains. In spite of the negligible strain caused by the phase transformation, it seems to be inevitable to form a certain small amount of a domains in the BaTiO3 film on MgO system.