Thermally generated [Li]0 centers in CaO

Thermal quenching of Li-doped CaO crystals annealed at temperatures in excess of 1400 K results in the formation of [Li]0 defects in the same manner as previously observed in Li-doped MgO crystals. These defects are lithium ions substituting for calcium and having a bound hole at a neighboring oxygen site which, unlike the same defects produced by low doses of ionizing radiation at low temperature, are stable against hole release well above room temperature. Three additional centers are observed in thermally treated CaO which are also stable well above room temperature and, of which at least two appear to involve holes and nearby Li+ ions. The four stable defects are also produced by high-dose electron irradiations at room temperature. The model previously proposed for MgO involving localized regions of high lithium concentration, can also account for the stability of the thermally generated defects in CaO