Mechanism of Point-Defect Formation in Ionic Crystals

Abstract

The energetics of point-defect formation in ionic crystals based on $V_K+e$ recombination has been investigated in detail. A sequence of [110] replacement collisions involving a neutral halogen atom is energetically possible and leads to the formation of well-separated $F$ and $H$ centers. Zero-point energy vibrational and librational amplitudes may lead to defocusing of the early collisions and to the creation of nearby $F$ and $H$ centers from which subsequently $F^{+}$ centers (vacancies) and $I$ centers (interstitial ions) can be formed. Direct formation of these charged centers by a replacement sequence is not possible.