Release behavior of hydrogen isotopes in deuterium-irradiated Li2TiO3

The release mechanism of tritium in breeding materials is one of the critical issues in fusion reactor. In this study, thermal desorption spectroscopy (TDS) experiments were performed at heating rates of 5, 10, and 15 K/min to elucidate the release kinetics of deuterium from trapping sites. The deuterium spectra for Li2TiO3 irradiated by deuterium ions in different heating rates featured an obvious peak at temperature ranging from 550 K to 800 K. The activation energy of deuterium release from Li2TiO3 is 0.53 eV. X-ray diffraction (XRD) results indicate that Li2TiO3 crystals are damaged by D+ irradiation, but no new phases are produced. After TDS experiments, the crystallinity of Li2TiO3 crystals recovers as that of unirradiated samples. Li2TiO3 samples become dark blue after annealing in vacuum and become white again after annealing in air. According to X-ray Photoelectron Spectroscopy (XPS), the surface compounds of colored Li2TiO3 have changed. This may be attributed to the formation of oxygen defect in reduction atmosphere.