Theoretical study of two possible occupation sites for tritium atoms in lithium titanate

Tritium breeder materials are fundamental to the development of a fusion reactor. One of the materials under investigation is lithium titanate, which has a good thermal stability, high density of lithium and low activation under irradiation, which are the fundamental properties that are demanded from this type of materials. However, there are little data on physical and chemical properties, which are necessary in order to design a material with the best characteristics to be used in a fusion reactor. We present a theoretical investigation on possible occupation sites for tritium atoms in lithium titanate structure using ab initio Hartree–Fock method. Two possible substitutional Li sites were identified for a tritium atom: one in the titanium layer and the other in the lithium layer. This study showed that the tritium released would favorably occupy positions in lithium layers than in titanium layers. Tritium occupying sites in titanium layers would require more energy to release in comparison to lithium layers. An interesting relation is seen between these results and experimental data.