The study of nickel impurity segregation on LSNT perovskite open surfaces by means of ab initio molecular dynamics

Abstract

In this paper, the segregation of the Ni impurity on open surfaces of the doped strontium titanate perovskite is investigated by means of ab initio molecular dynamics method based on the density functional theory and applied to a model periodic cell with stoichiometry La0.5Sr0.5TiO3 (LST).The performed studies are based on recent experimental observations on the segregation of Ni impurity atoms and their tendency to form clusters at the boundaries of defect structure of La0.2Sr0.7Ni0.1Ti0.9O3-δ (LSNT) perovskite. The results of the first-principles calculations of segregation energy showed that Ni does actively segregate toward the open surfaces. It was found that during segregation, nickel atoms leave the crystal volume to the perovskite surface and rise above its upper layer. Thus, the obtained results confirm the experimental data on the segregation and formation of nickel clusters on open LSNT surfaces.