Structure of D2O ice VIII from i n s i t u powder neutron diffraction

Structural parameters for D2O ice VIII have been determined by Rietveld refinement of time-of-flight powder neutron diffraction data collected in situ at 28 kbar and −4 °C. The D2O molecule has a bond length of 0.973 (11) Å and a bond angle of 104(2)°. O–D⋅⋅⋅O bonds are slightly bent with an angle of 177(1)°. Thus, the D2O molecules in ice VIII are essentially identical to those observed in other high pressure ice structures for which accurate structural data are available.