The influences of deuterium irradiation defects on mechanical properties for ceramic breeder material Li2TiO3

Tritium breeder materials are significant for blanket design of fusion reactor. However, during blanket operation, the ceramic breeder materials will be subject to neutron irradiation, which could be detrimental to mechanical properties. Because of good chemical stability and available tritium release behavior, Li2TiO3 is becoming one of candidate ceramic breeder materials. In this study, Li2TiO3 samples are irradiated by 120 keV deuterium ions. For sample characterization, the phase composition is investigated by X-ray diffraction (XRD) before and after irradiation. After deuterium irradiation, the Electron Spin Resonance (ESR) experiments are employed to investigate the irradiation defects. Micro-hardness measurement is applied to study the changes of mechanical properties. XRD results indicate that Li2TiO3 crystals are damaged by deuterium irradiation, but no new phases are produced. According to ESR experiment, the main defect type after deuterium irradiation is F-center which are vacancies trapping one electron. According to Vickers hardness measurement, size effect of micro-hardness is observed. The Meyer coefficient obtained in the experiment is 1.65, which is less than 2. Vickers hardness increases as applied loads decrease which are consistent with Meyer theory. And Vickers hardness of Li2TiO3 decreases as irradiation doses increase.