High-pressure Brillouin study on hydrogen chloride up to 8 GPa

The ratios of adiabatic elastic constants to density, acoustic velocity, and refractive index in the liquid phase and the orientationally disordered phase of hydrogen chloride have been determined under pressures up to 8 GPa at 300 K, by applying the method of least-squares fit to the direction-dependent acoustic velocities obtained by Brillouin spectroscopy. It is found that the average of the least-square error shows the abrupt increase at about 4.5 GPa, which indicates the existence of the solid I to I ' phase transition. (C) 1999 Elsevier Science B.V. All rights reserved.