Influence of O-related defects introduced by reduction on release behavior of hydrogen isotopes in Li2TiO3

Abstract

In fusion reactors, Li2TiO3 is one of the most promising candidates among solid breeder materials. However, Li2TiO3 will be reduced after heating under a reducing atmosphere resulting in a deficiency of oxygen. In the present study, the O-related defects introduced by reduction and their effect on the release behavior of hydrogen isotopes in Li2TiO3 were investigated by means of Raman spectroscopy, electron spin resonance and thermal desorption spectroscopy. O-related defects were confirmed as E-centers by electron spin resonance. The concentration of defects increased as the exposing temperature increased and then decreased when the temperature increased higher above 750 °C. The color of Li2TiO3 samples changed from white to dark blue after heating under deuterium and recovered to white again after annealing in air. This color change suggested a change from Ti4+ to Ti3+ due to a decrease in the oxygen content. Raman spectroscopy results indicated that there are no modifications in Li2TiO3 crystal structure, but on crystallinity. Thermal desorption spectroscopy showed the release behavior of deuterium has been affected considerably by O-related defects.