Equilibria of hydroxyl defects in MgO

Isochronal annealing studies were carried out on slow-cooled MgO single crystals. The annealing behaviour of the hydroxyl defects is consistent with a defect model in which brucite precipitates dissolve in MgO forming OH-V-OH defects with a heat of solution equal to 0.45 eV. These OH-V-OH defects further dissociate into V_OH^–defects and hydroxyl ions with a dissociation energy of 0.82 eV.