Structural Studies of Molecular Ices at High Pressure

Abstract

Recent developments in high-pressure diffraction techniques using both neutron and synchrotron x-ray sources now allow accurate studies of ices over a wide range of pressures. Results are revealing complex and unexpected behaviour. The disorder in ice VII is found to be different from that previously thought and to give rise to a complex H-bond geometry. The ammonia molecules in ammonia phase IV are found to orientationally ordered with a bifurcated H-bond geometry which becomes more distorted with increasing pressure. And hydrogen sulphide phase-F is found to have a partially ordered structure where H-bonding plays a more significant role than at ambient pressure. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.