Crystal structure of the tetragonal ɛ-phase deuteride of Ti–15 at%Mo alloy determined by neutron diffraction

The crystal structure of the deuteride of Ti0.85Mo0.15 alloy Ti0.85Mo0.15D1.47 is determined by neutron powder diffraction to be a tetragonally distorted fluorite-type structure similar to that of ɛ-phase in Ti–H system. The D concentration and c/a axial ratio of this phase are significantly lower than that in the Ti–H system. The formation of ɛ-phase in the Ti–Mo–H system supports the hypothesis that the electron density change play a role in the δ–ɛ phase transition. Considerable broadening of the reflections is observed in the diffraction patterns, and attributed to the D concentration inhomogeneity and anisotropic microstrain in the lattice of the deuteride.