A study was made of the atomic structure of [001]90° rotation twin walls in orthorhombic CaTiO3 (symmetry Pbnm) at 10K and their effects on O vacancies. The wall thickness was found to be 2.3nm at temperatures far below Tc and it was found that it was energetically favorable for such vacancies to reside in the wall, particularly when bridging titania ions in the (001) plane. The binding energy of an O vacancy in the wall with respect to the bulk was calculated to be up to 1.2eV.

Trapping of Oxygen Vacancies on Twin Walls of CaTiO3 - a Computer Simulation Study. M.Calleja, M.T.Dove, E.K.H.Salje: Journal of Physics - Condensed Matter, 2003, 15[14], 2301-7