Radiation damage induced by neutron irradiation was studied by optical absorption measurements in undoped MgO crystals and in MgO crystals intentionally doped with either H or Li impurities. The O-vacancy concentration incurred by the neutron irradiation increased with neutron dose. Suppression of radiation damage as characterized by O vacancies was observed in MgO:H crystals and attributed to migration of O vacancies to microcavities filled with H gas. In MgO:Li crystals irradiated with neutron doses below 1018/cm2, most of the O vacancies were camouflaged as hydride ions formed by the capture of protons by the O vacancies. Substitutional Li ions were also displaced. It was postulated that they aggregated at Li2O precipitates. Thermal annealing experiments demonstrated that protons were mobile at 700K and Li ions at 1100K.

Role of Hydrogen and Lithium Impurities in Radiation Damage in Neutron-Irradiated MgO Single Crystals. R.González, I.Vergara, D.Cáceres, Y.Chen: Physical Review B, 2002, 65[22], 224108 (7pp)