Disordered structure of D2O ice VII from in situ neutron powder diffraction

Neutron powder diffraction data have been collected for the ice VII phase of D2O at 26 kbar and 22 °C by the time‐of‐flight technique. The data confirm the cubic Pn3m space group with completely disordered hydrogen bonding. Rietveld analysis of the data to obtain a bond length and bond angle for the D2O molecule is hampered by combined static and thermal disorder of both the deuterium and oxygen atom positions. However, simple models give results which are consistent with the D2O molecule parameters for other ice structures.