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Laser-Raman spectra of hexagonal H2O and D2O ice have been measured in the frequency range 100–350 cm−1, temperature range 25–272 K, and pressure range 1–1600 bar. The frequency of the main peak due to translational lattice vibrations νT, which appears near 220 cm−1, decreases with increasing temperature at an increasing rate. νT increases linearly with applied pressure. An analysis of the variation of νT with temperature and pressure shows that ∼55% increase in νT on cooling is due to the intrinsic dependence of translational vibrations on temperature and ∼45% due to the accompanied decrease in the distance between the nearest oxygen atoms in ice. For the same amount of decrease in the distance, isobaric cooling increases νT twice as much as isothermal compression near 255 K. The Grüneisen constant −(∂ ln νT/∂ ln V) is 1.84 at 255 K. The contribution to the refractive index and permittivity from translational vibrations has been calculated over a wide range of temperature. The decrease in the limiting high frequency dielectric permittivity of ice with decreasing temperature or increasing pressure is qualitatively consistent with the observed change in the main frequency of lattice vibrations.

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The effect of sample and grain size on the uniaxial compressive strength of polycrystalline ice has been investigated at -10·C, at a strain-rate of 5.5 x 10-4 S-1. The results show (a) that the sample size must be 12 or more times greater than the grain size for it to have no effect on the strength and (b) that there is no significant dependence of compressive strength on grain size, within the grainsize range of 0.6 to 2.0 mm. INTRODUCTIONTwo of the possible variables that might affect the strength of polycrystalline ice, as determined in laboratory experiments, are the size of the sample being tested, and the size of the individual grains in the sample. We report here tests done at -10·C in uniaxial compression, at a strain-rate of 5.5 x 10-4 S-1, to investigate these effects.The effect of grain size is of particular importance because of conflicting results in the literature. Muguruma (1969) founrl that the maximum stress for columnar-grained ice varied linearly with the inverse square root of the grain diameter, within the grainsize range from 2 to 5 mm. However, Bromer and Kingery (1968) found that the viscosity of columnar-grained ice was proportional to the grain size squared. B~ker (1978) found a more complicated relationship in that the creep rate ~ was related to grain size d by ~ « d N whe re N = -2.35 for d < 1.0 mm and N = +2.5 for d > 1.0 mm. Duval and LeGac (1980), however, found that the creep rate was independent of crystal size. We, therefore, thought that it would be worthwhile to try and settle this matter by testing many samples at one temperature and one strain-rate.Preliminary results have been published in Jones and Chew (1981).