Dependence of gamma-ray dose on annihilation processes of irradiation defects in Li2TiO3

Dependence of gamma-ray dose on formation and annihilation behaviors of irradiation defects was studied by means of ESR. In the formation behavior of irradiation defects, the amount of irradiation defects and ratio of O2--center to O--center increased as the in gamma-ray dose increased. The annealing experiments showed that the amounts of E'-center and O-related defects which are the Frenkel pair decreased in the two temperature ranges of 300-400 and 550-650 K. The first and second stages were identified to reactions between E'-center and O--center and E'-center and O2--center, respectively. By comparing annihilation with formation behaviors of irradiation defects, it was revealed that the activation energy of annihilation for irradiation defects was influenced by the ratio of O2--center and O-related defects. Therefore, the annihilation process of irradiation defects was dominated by pyrolysis of O2--center.