Energy of formation of intrinsic defects and their clusters in the powellite CaMoO-=SUB=-4-=/SUB=-

Abstract

Atomistic simulation of powellite crystals has been carried out. A system of parameters of interatomic potentials is proposed for the calculation of point defects in powellite. The formation energies of intrinsic defects and their clusters, which are spatially related combinations of defects, are estimated. The most favorable localization of interstitial calcium and oxygen ions was determined. The formation energies of the Frenkel and Schottky defects are calculated. It was shown that the most energetically preferred in stoichiometric powellite are the oxygen Frenkel defects. Defects arising from deviations from stoichiometry are considered. It is established that the clustering of defects allows to reduce the energy of their formation by 15-20%. Keywords: powellite, tungstates and molybdates, atomistic simulation, intrinsic defects.