New insights into the effect of zirconium dopant on tritium release from Li2TiO3 (001) surface from first-principles calculation

The influence of zirconium (Zr) dopants on tritium release from Li2TiO3 (001) surface was researched by density functional theory (DFT) calculations. The energy barriers for T2 and T2O molecules formation on undoped and doped surfaces were calculated and compared by using climbing-image nudged elastic band (CI-NEB) method. It was found that T2O is more easily generated than T2 on the surfaces. And Zr dopants can significantly promote the production and release for T2O on the surface of Li2TiO3. Especially when Zr atoms doping ratio is to be 3.12 atom % (Zr3), the barrier of T2O formation changed from 0.97 eV on undoped surface to spontaneous formation on doped surface. The energy barrier for T2O desorption on the surface also decreases to a smaller energy barrier of about 0.42 eV. Although the catalytic effect of Zr doping on T2 formation on the surface is relatively weak. The electronic characteristics show that the doping of Zr atoms can influence the charge transfer of surface atoms, making OT group more likely to appeal to adjacent T atom, which may be the reason for promoting the formation of T2O by Zr dopants. This study can provide useful details for the effect mechanism and catalytic behavior of Zr dopants on the release of tritium from Li2TiO3 surface.