Ab initio study of Be and Be12Ti for fusion applications

The paper applies ab initio methods for investigation of possible origin of the easier tritium release from titanium beryllide Be12Ti as compared with that of beryllium. Both materials are considered as neutron multiplier materials in some design concepts of tritium breeding blanket of future fusion reactor. The only stable tetragonal crystal structure of Be12Ti was studied in this work. Hydrogen solution energy in all non-equivalent interstitial positions of Be12Ti was found to be lower than that for beryllium suggesting easier dissolution of hydrogen atoms in Be12Ti. Maximal binding energy of hydrogen atoms in vacancy linearly decreases with the number of hydrogen atoms both in beryllium and Be12Ti. The highest hydrogen binding in a vacancy is 0.4 eV lower in Be12Ti, predicting easier release of hydrogen from beryllide with respect to beryllium. No formation of chemical bonds between hydrogen atoms inside both beryllium and Be12Ti vacancies was observed.