Theoretical Solution Energy of Alkaline Earth Ions in Lanthanum Chromites

Abstract

First principles calculations by a plane-wave basis pseudopotential method have been made for Mg, Ca, and Sr-doped lanthanum chromites (LaCrO₃). A supercell composed of 40 atoms of a high temperature phase of LaCrO₃ having a cubic-perovskite structure has been used. Solution energies of a neutral solute and a compensated solute by an oxygen vacancy were systematically computed. They were obtained for two kinds of cation sites and four thermodynamical conditions with different chemical potentials of constituent atoms. Mg shows lowest solution energy when it substitutes for the Cr ion. On the other hand, both Ca and Sr prefer to be located at La site. The charge neutral states are preferred by all of them. The results are consistent to experimental results regarding the site preference and the charge state.