Atomic structure and properties of the (310) symmetrical tilt grain boundary (STGB) in SrTiO₃. Part I: Atomistic simulations

The relaxed structure and energy of the (310) symmetrical tilt grain boundary (STGB) in SrTiO₃ have been calculated using static lattice energy minimization methods. In principle, the (310) GB plane can either be a cation-rich, positively charged 'SrTiO' plane or a negatively charged oxygen plane, and both scenarios have been considered in this report. The effect of point-defect reconstruction at the GB core region, manifested either as completely missing columns or as half-filled columns of ions as suggested by experiments, has been analyzed. The results indicate that while Schottky defects are very strongly preferred energetically at the GB core, there is not significant gain in energy by having half-filled columns, as opposed to fully-dense and fully-empty columns, at the GB core. The simulation results have been analyzed in the context of Pauling's rules of crystal chemistry and bicrystallography. The results form the basis for an objective comparison with experimental studies in Part II of the paper.