Domain structures in the perovskite-type heteroepitaxial ferroelectric thin films

Heteroepitaxial PbTiO3 and (Ba1-xSrx)TiO3 thin films were obtained by the RF sputtering method. The (100) cuts of MgO single crystals were used as substrates. The films exhibited ferroelectric properties closely similar to those of the ceramic targets. Depending on substrate temperature (Ts) with other deposition parameters constant, heteroepitaxial films of various degree of perfection of the crystalline structure were obtained. It has been found that the crystal structure of the PbTiO3//(100) MgO and (Ba1-xSrx)TiO//(100)MgO films for x<0.3 at room temperature belongs to the tetragonal system P4mm. Phase transitions in the (Ba1-xSrx)TiO3//(100)MgO films unlike those in the PbTiO3//(100)MgO films exhibited marked broadening. The domain structure of the heteroepitaxial films in comparison with that of the free ferroelectric single crystals shows certain singular features. The PbTiO3//(100)MgO films exhibit characteristic a-c-domain structure while the (Ba1-xSrx)TiO3//(100)MgO films have c-c-domain structure.