A-site Diffusion in La_(1-x)Sr_xMnO_3: Ab Initio and Kinetic Monte Carlo Calculations

摘要

We have investigated the migration of La~(3+) and Sr~(2+) by an A-site vacancy (V_a) mechanism in La_(1-x)Sr_xMnO_3 (LSMO). Ab initio calculations determine migration barriers of 2.96 eV and 2.42 eV, for La~(3+) and Sr~(2+), respectively, and that repulsion between Sr~(2+) and V_A is well-described by a screened electrostatic potential of the form E = 2.8 exp(-0.2r)/r eV, (r being separation in A). Using these results to parameterize kinetic Monte Carlo (KMC) and analytical calculations for diffusion coefficients we find good agreement with experiment observations of A-site diffusivity in other perovskites. We use these results to consider the tendency for Sr~(2+) to kinetically demix.