Existence of ferroelectric ice on planets—A neutron diffraction study

From neutron powder-diffraction experiments, we have studied the growth process of ferroelectric ice XI (eleven) with deuteron-ordered arrangements. We measured time-resolved neutron diffraction of 0.001-M KOD-doped D2O ice. We observed the growth of ice XI at 72–74 K. The mass fraction f (the ratio of mass of ice XI to that of the doped ice) linearly increased with time for about 2 days. The de-transformed ice Ih, obtained after warming above the transition temperature of 76 K, retransformed to ice XI at 66 K. The observed increase of f with time is in good agreement with the nucleation process of the ordering and the constant growth of the ordered domain. A large fraction of ice Ih sample doped with sodium hydroxide changed to ice XI at 68 K. The results suggest that large quantities of ice on cold icy bodies in our solar system are able to transform to ice XI, which may be detectable by space telescope and planetary exploration.