Crystal structure change of Li2+xTiO3+y tritium breeder under moist air

To investigate the aging behavior of Li2+xTiO3+y, the materials Li2.0TiO3+y, Li2.2TiO3+y and Li2.4TiO3+y were stored under moist air at ambient temperature. Under these conditions the weight of Li2.0TiO3+y increased by only 1% in 100 days, which provides evidence for the high chemical stability of Li2TiO3. In comparison, under the same storage conditions the weights of Li2.2TiO3+y and Li2.4TiO3+y increased by 14% and 18%, respectively. The observed weight gain is attributed to the uptake of water, and to the reaction of a by-product of Li2+xTiO3+y with water and carbon dioxide. The weight gain curves were evaluated by the Jander equation. From the analysis, it was possible to obtain the diffusion coefficient of water through Li2TiO3 particles at ambient temperature. The determined value was 2 × 10−17 m2/s.