Hydrogen interactions with intrinsic point defects and hydrogen diffusion in tungsten doped Al2O3

In light of the extensive use of tungsten (W) in fusion experimental devices and the importance of hydrogen isotopes permeation, based on the first principle approaches we study the effects of W doping on the formation energies of intrinsic point defects, hydrogen interactions with such defects, and hydrogen diffusion in bulk of alpha-Al2O3. Our investigation demonstrated that W doping enhances the formation of oxygen and aluminum vacancies (Vo and VAl) in alpha-Al2O3. In W doping alpha-Al2O3 , hydrogen primarily exists in the form of Ho- (hydrogenation of the bulk V-O(3-)) and Hi(-) (H interstitial) defects, while it hardly occupies VAl. Hydrogen is firmly trapped by Vo with a formation energy -3.35eV, and Hi(-) diffusion become extremely challenging because W doping significantly raises the Hi(- )diffusion barrier to 4.44 eV. Our findings indicate that W doping is beneficial for hydrogen permeation resistance in alpha-Al2O3 .