Diffusion of a tritium interstitial in Li4TiO4 from first-principles calculations

Li4TiO4 is an attractive tritium breeding material due to its high lithium density for the application in fusion reactors. Diffusion in the crystal lattice is a vital step of the tritium release process. In this paper, we report the diffusion of a tritium interstitial in the Li4TiO4 crystal from first-principles calculations. The tritium interstitial sites, diffusion paths and activation energies of diffusion are obtained. We find the most favorable tritium diffusion path is along <001> of the Li4TiO4 crystal with an activation energy of 0.410 eV. The activation energy is 0.366 eV for tritium at 450 K after the vibrational correction is applied. The calculated activation energy is in good agreement with the experimental value of 0.370 eV.