A theoretical study of the energies of formation of point defects in CaF2 and UO2

Abstract The Born model of the ionic crystal is used to calculate the energies of formation of point defects in CaF2 and UO2 in the zeroth, first and second orders. The results of calculation, to all orders, indicate that anion-Frenkel pairs are the intrinsic defects in CaF2 and are in agreement with previous calculations. In UO2 the zeroth-order calculation predicts anion-Frenkel pairs as the intrinsic defects, whereas the higher-order calculations indicate that Schottky defects are the intrinsic defects. It is concluded that Schottky defects are the intrinsic defects in UO2 with an energy of formation of about 7 ev.