NEUTRON-SCATTERING STUDIES OF STRUCTURAL TRANSFORMATIONS AND VIBRATIONAL-SPECTRA OF ICE AFTER HIGH-PRESSURE TREATMENT

The transitions of the recovered high-pressure phase ice VIII first to high-density amorphous (hda) and low-density amorphous ices, and fina lly to cubic Ic, and hexagonal Ih ice were observed at heating using r eal-time neutron diffraction. Inelastic incoherent neutron scattering measurements on the hda ice, ice Ih and high-pressure phase ice VI rev ealed similarity between the amorphous phase and crystalline ice VI an d led to the new proposition that hda ice consists of two interpenetra ting hydrogen-bounded networks with no hydrogen bonds between ''sublat tices''.