Diffuse neutron-scattering study of deuterated ice Ih

Abstract

A series of measurements of the diffuse scattering from D₂O ice Ih have been performed on SXD at ISIS using the neutron time-of-fight Laue diffraction technique. A large region of reciprocal space was covered in the three main planes of the hexagonal lattice, h k 0, h h l and h 0 l, at 20 K, and also in the h k 0 plane at 10, 110, 160 and 250 K. The data show highly structured strong diffuse streaks, which are predominantly a result of static disorder in the lattice. Not all this scattering can be explained in terms of the Bernal-Fowler rules, as a comparison with simulation shows. The changes in scattering in the h k 0 plane with increasing temperature appear to be consistent with an increase in atomic thermal vibrations, suggesting that the structural feature causing the scattering over and above the Bernal-Fowler prediction is present up to 250 K.