| Research Abstract |
We have determined acoustic velocities in any direction, refractive index, adiabatic elastic constants, and adiabatic bulk modulus of H_2O and D_2O ices at 300K and at pressures between 1.05 and 2.1 GPa for tetragonal ice VI and above pressures up to 8 GPa for cubic ice VII.Typical values of elastic constants for H_2O ice VI are C_<11>=32.8, C_<12>=11.8, C_<13>=14.7, C_<33>=27.8, C_<44>=6.3, and C_<66>=5.9 GPa at the pressure of 1.23 GPa Moreover, for H_2O ice VII the values of 3 elastic constants are C_<11>=57, C_<12>=31, and C_<44>=32, GPa at P=4.7 GPa. Refractive index and elastic constants show no distinction between H_2O and D_2O over the observed pressure ranges. At ice VI*VII transition at 2.1 GPa, acoustic velocities, refractive index, and elastic constants present drastic change, but the adiabatic bulk modulus shows almost continuous change which is most likely to relate the common features of the selfclathrate structure and the potential function in both VI and VII ices.
These results studied by Brillouin Spectroscopy are noticeable in the high-pressure world.
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