First-Principles Study of Tritium Diffusion in the Li₃TaO₄ Crystal

Abstract

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.

First-Principles Molecular Dynamics Simulation on High Silica Content Na3AlF6–Al2O3–SiO2 Molten Salt

“…As a classic computational simulation method, first-principles molecular dynamics simulation calculates ionic interactions directly from first-principles, while requiring no fitting to the experimental data. It has been applied to KCl–LiCl, , CaO–CaSiO 3 , KF–NaF–AlF 3 –Al 2 O 3 , Li 3 TaO 4 , and FeAsS systems successfully.…”

Ab Initio Simulations of Tritium Diffusion in Al-Rich Iron Aluminide Coating Phases

“…Numerical simulations performed for Li 3 TaO 4 , a potential tritium breeding material, indicated that tritium diffusion could decrease from 10 −9 m 2 •s −1 in a perfect crystal lattice to 10 −12 m 2 •s −1 for tritium hopping out of a Li vacancy. 37…”

“…However, it is interesting to note that vacancy defects could further slowdown tritium diffusion in breeding materials. Numerical simulations performed for Li 3 TaO 4 , a potential tritium breeding material, indicated that tritium diffusion could decrease from 10 –9 m 2 ·s –1 in a perfect crystal lattice to 10 –12 m 2 ·s –1 for tritium hopping out of a Li vacancy …”