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Using a recently established BaTiO3 potential model specifically designed for the calculation of defect energetics, atomistic simulations have been carried out on the intrinsic defect chemistry and Rare Earth (RE3+) doping of hexagonal barium titanate (h-BaTiO3). Five charge compensation schemes have been considered as well as potential cluster binding energies. The results show that ion size arguments are obeyed. In the dilute concentration limit, large RE3+ cations dope at the Ba-site via a titanium vacancy mechanism and mid sized RE3+ cations dope at the Ba and Ti sites simultaneously via a self compensation mechanism. In contrast, small RE3+ cations dope exclusively on the Ti-site via an oxygen vacancy compensation scheme. Comparisons between the hexagonal and cubic phases of BaTiO3 have also been drawn. It is suggested that Ba-site doping is less favorable and that Ti-site doping is considerably more favorable in h-BaTiO3 and that different defect configurations have a significant effect on the binding energies between such defects, leading to some mechanisms becoming more or less energetically favorable as a result. [ABSTRACT FROM AUTHOR]

Focuses on a study which demonstrated a method for the atomistic modeling of metal/oxide interfaces, even when these are complicated by charged defects and space charge in the oxide. Calculation of the structure and energies of silver/magnesium oxide interfaces; Image interactions between the ionic charges and the metal; Fluctuations in the induced charge distribution.