Synthesis and reactivity of single-phase Be₁₇Ti₂ intermetallic compounds

Highlights: • Preliminary synthesis of single-phase Be₁₇Ti₂ was succeeded. • Reactivity difference between beryllium and beryllides may be caused by a lattice strain. • Oxidation of Be₁₇Ti₂ at high temperatures results in the formation of TiO₂. • Simulation results reveal that a stable site for hydrogen at the center of tetrahedron exists. - Abstract: To investigate feasibility for application of Be₁₇Ti₂ as a neutron multiplier as well as a refractory material, single-phase Be₁₇Ti₂ intermetallic compounds were synthesized using an annealing heat treatment of the starting powder and a plasma sintering method. Scanning electron microscopic observations and X-ray diffraction measurements reveal that the single-phase Be₁₇Ti₂ compounds were successfully synthesized. We examined the reactivity of Be₁₇Ti₂ with 1% H₂O and discovered that a larger stoichiometric amount of Ti resulted in the formation of TiO₂ on the surface at high temperatures. This oxidation may also contribute to an increase in both weight gain and generation of H₂. This suggests that the formation of the Ti-depleted Be₁₇Ti_2−x layer as a result of oxidation facilitates an increased reactivity with H₂O. To evaluate the safety aspects of Be₁₇Ti₂, we also investigated the hydrogen positions and solution energies based on the first principle. The calculations reveal that there are 10 theoretical sites, where 9 of these sites have hydrogen solution energies with a positive value (endothermic) and 1 site located at the center of a tetrahedron comprising two Be and two Ti atoms gives a negative value (exothermic).