Calculating Surface Energies of Lead Magnesium Niobate Using Density Functional Theory

Abstract

ABSTRACTComputations involving density functional theory have been performed on lead magnesium niobate (PMN) single crystal models in an effort to calculate their surface energies, which are believed to play a role in brittle fracture mechanisms. To establish credibility of this approach, test calculations were performed on MgO and SiC single crystal models. The surface energy of MgO was determined to be 1.2 J/m2, which is in close agreement with the experimental value. Similarly, the value for SiC, 8.03 J/m2, supported a level of confidence with this methodology. Surface energies were calculated for several simple perovskites and several PMN models. The calculated values suggest that changes in the A-site ion of PMN do not result in any significant changes in the surface energies.