Tetragonal BaTiO3 thin films hydrothermally grown on TiO2 single crystals

Tetragonal BaTiO3 films were prepared on single crystal TiO2 substrates by the hydrothermal method. The films were grown in 0.5 M Ba(OH)2 aqueous solutions at 150°C and 200°C during 4 h. X-ray diffraction analysis demonstrated the presence of polycrystalline BaTiO3 in its tetragonal phase, in contrast to hydrothermally grown BaTiO3 on metallic substrates, which usually results in the cubic phase under similar conditions. Rutherford backscattering measurements in the channeling mode showed that the barium ions did not occupy lattice positions and that there is not a sharp film–substrate interface. The diffusion range of the moving species — either Ti or Ba — was about 1 μm, and the diffusion coefficient at 150°C was estimated to be about 10−16 m2 s−1.