Electric polarization behavior of MgO : Li+ crystals upon quenching from above 1400 K

Abstract

Crystals of Li⁺‐doped MgO which have been quenched from temperatures in excess of 1400 K exhibit an extraordinarily large polarization in an electric field, and the temperature dependence of the relaxation time of this polarization, as measured by both dc (thermal depolarization) and ac (loss tangent versus frequency) methods, indicates a relaxation activation energy of 0.6–0.73 eV, which is consistent with the ionization energy of [Li]° centers. This polarization behavior is to be expected for small semiconductor inclusions (regions of high [Li]° center density embedded in a dielectric) and supports the ’’microgalaxy’’ model of Chen et al. to account for stable [Li]° centers in annealed and quenched MgO : Li⁺ crystals.