Effects of Li4TiO4 structure on tritium release kinetics from lithium-enriched Li2+xTiO3

The release kinetics of tritium for Li2+xTiO3 (x = 0, 0.2, 0.4) and Li4TiO4 were studied by means of Thermal Desorption Spectroscopy (TDS). Tritium-TDS spectrum at the heating rate of 0.5 K / min for Li2+xTiO3 irradiated with thermal neutron consisted of two release stages at 480 K and 580 K, namely Peaks 1 and 2, respectively. The activation energy of Peak 1 was estimated to be around 0.37 eV, while that of Peak 2, about 0.63 eV. The latter corresponded to the activation energy of tritium diffusion in Li2TiO3. For Li4TiO4 exposed to tritium-deuterium mixture gas, two tritium release stages named as Peaks A and B were also observed at 450 K and 600 K, respectively, in tritium-TDS spectrum at the heating rate of 0.5 K / min. As the release temperature regions of Peak 1 and Peak A were almost the same, tritium releases of these peaks were considered to be originated from a same process. O-T bonds formed on the surface of Li4TiO4 were decomposed as Peak B in TDS spectra. (author)