Neutron scattering studies of ordered gamma -ZrD

Abstract

The crystal structure and the lattice dynamics of the ordered gamma -ZrD phase were studied by means of neutron diffraction and inelastic neutron scattering (INS). It was found that the actual structure of the gamma phase is orthorhombic, space group Cccm, rather than tetragonal as previously believed. The one-phonon deuterium optical band in the INS spectrum was observed at an energy transfer of 107 meV (with the main feature at 103.4 meV), which is higher than the deuterium vibrational energies for all other phases of the Zr-D system. Distinct features were also observed in the INS spectrum below the free multiphonon bands, which were explained as the bound multiphonon states.