Oxidation and reduction of lithium-containing MgO at high temperatures

The effect of oxidation and reduction on Li-containing MgO crystals at temperatures up to 1600 K is reported. Heating in oxidizing atmospheres followed by fast cooling produces stable [Li]^∘{} defects, whereas similar treatment in a reducing atmosphere does not. Annealing rates of these defects also depend on whether the crystals are in an oxidizing or reducing atmosphere. A short-range diffusion mechanism is proposed to describe the atmospheric dependence of [Li]^∘{}-defect production. Heating to {~} 1500^∘{}K, regardless of the ambient atmosphere, gives rise to a broad optical absorption band at {~} 5.3 eV, which we believe to be associated with lithium. Optical excitation of this band produces a luminescence which peaks near 2.7 eV.