Trapping of oxygen vacancies on twin walls of CaTiO3:: a computer simulation study

We have studied the atomic structure of [001]90degrees rotation twin walls in orthorhombic CaTiO3 (symmetry Pbnm) at low temperature (10 K) and their effects on oxygen vacancies. The wall thickness was found to be 2.3 nm at T much less than T-c and it was found that it is energetically favourable for such vacancies to reside in the wall, particularly when bridging titania ions in the (001) plane. The binding energy of an oxygen vacancy in the wall with respect to the bulk is calculated to be less than or equal to 1.2 eV.