Epitaxial Ba1–xSrxTiO3 films, with x = 0.5, were grown onto MgO substrates by using pulsed-laser deposition. A high density of antiphase domain boundaries was observed in the films. The formation of the antiphase domain boundaries was attributed to the differing crystal symmetries of the film and the substrate. Adjacent domains had an in-plane phase shift of ½[110] or ½[1¯10], thus creating a phase shift of the in-plane lattice planes of ½[010] or ½[100] across the boundary. First-principles calculations were used to obtain the effect of the antiphase domain boundaries on the dielectric constant of SrTiO3 and it was found that they lowered the effective in-plane dielectric constant in the direction normal to the antiphase domain boundaries. Upon annealing, the density of antiphase domain boundaries decreased and the dielectric properties improved.

Origin of Antiphase Domain Boundaries and their Effect on the Dielectric Constant of Ba0.5Sr0.5TiO3 Films Grown on MgO Substrates. H.Li, H.Zheng, L.Salamanca-Riba, R.Ramesh, I.Naumov, K.Rabe: Applied Physics Letters, 2002, 81[23], 4398-400