Neutron scattering studies of the structure and lattice dynamics of a solid solution of hydrogen in -manganese

A solid solution of hydrogen in -Mn, -MnHx with xD 0:073, was prepared at 623 K and a hydrogen pressure of 0.85 GPa. A profile analysis of the neutron diffraction patterns measured at 225 K and at 300 K showed that hydrogen in-MnH0:073 randomly occupies the interstitial positions 12e (0, 0, 0.538) of the -Mn host lattice. An inelastic neutron scattering study of -MnH0:073 at 90 K revealed a pronounced peak at 6.4 meV and a rather broad optical hydrogen band with peaks at 73, 105 and 123 meV. The splitting of the optical band into three different modes agrees with the low symmetry, 2, of the 12e hydrogen sites. A tentative interpretation is given for the peak at 6.4 meV.