First-Principles Study of Tritium Diffusion in the Li₃TaO₄ Crystal

Li₃TaO₄ with a high melting point, good thermal stability, and higher lithium content has become a possible choice for breeder materials, which have potential applications in future fusion reactors. Perfect and defect crystal models of Li₃TaO₄ are set up, and all of the tritium-diffusion pathways have been studied by the first-principles method. The activation energy barriers of different diffusion pathways are calculated and analyzed considering the pathway length and tritium-oxygen interactions. The obtained minimum energy barrier for tritium diffusing in the perfect Li₃TaO₄ crystal is only 0.34 eV. The minimum energy barrier is less than 0.72 eV when tritium diffuses in the defect Li₃TaO₄ crystal in the presence of a lithium vacancy. Finally, the diffusion coefficients of tritium in the Li₃TaO₄ crystal are calculated, which further confirm that it is easy for tritium to escape from the trap of the lithium vacancy and diffuse in the crystal. Such a tritium-diffusion behavior is in favor of the tritium-release process of the Li₃TaO₄ crystal and could provide theoretical guidance for the future applications of Li₃TaO₄ materials.