Structural Modification and Domain Structure in a BaTiO3 Film on (110) SrTiO3

An unconventional pseudo tetragonal crystal structure is demonstrated in a BaTiO3 (BTO) epitaxial thin film grown on a (110) SrTiO3 (STO) substrate by pulsed laser deposition. The crystal structure of the BTO film, one of whose principal axes is shorter than the other, is markedly different from the bulk tetragonal structure. The pseudo tetragonal structure would be caused by the nearly uniaxial strain due to the different strain relaxation along the [001] and [110] axes. An irregular 90 degrees domain structure observed by piezo response force microscopy (PFM) is understood on the basis of a possible small elastic strain at the domain boundary in the pseudo tetragonal crystal structure. (C) 2013 The Japan Society of Applied Physics