Diffuse neutron scattering studies of ice Ih as function of temperature

Complete text of publication follows. A series of diffused neutron scattering measurements from D2O single crystal of ice Ih were made on Prisma at ISIS. The diffraction scan covers initially the (hh0) and (h00) reciprocal (Basal) plan at temperatures of 4, 150 and 230 K. At the low temperature of 4 K, the diffused scattering is very similar to early measurements made on SXD (J.C. Li, V.M. Nield, D.K. Ross, R.W. Whitworth, C.C. Willson and D. Keen, Phil. Mag. 69 (1994) 1173), but with better resolution and a larger Q coverage up to (990) along one of the main reciprocal directions. At high temperatures, the diffused scattering changes very drastically. Clearly double-curved diffuse streaks were observed. The curvature and the intensity of the streaks increase while temperature increases. The cause of the change of the diffused scattering pattern is not very clear, one possibility of H-contamination leading to a massive increase of phonon modes at low energy region can be removed based on a separated inelastic incoherent scattering measurement using TOSCA which shows no peaks at 110, 200 and 420 meV. These peaks are always associated with H vibrations. Other possibilities are currently under consideration. (author)