Dielectric Behavior of Cubic and Hexagonal Ices at Low Temperatures

Abstract

Cubic ice Ic and hexagonal ice Ih were prepared in pressurizable dielectric cells at temperatures near − 110°C from the high-pressure ices II and IX. No differences were found between the dielectric properties of Ic and Ih. Freshly prepared samples exhibited longer relaxation times at low temperatures than those commonly found for samples of Ih prepared directly by freezing purified water. These long relaxation times became appreciably shorter with sample aging. These results are attributed to precipitation of impurities from ices II and IX, followed by their gradual reincorporation in the ice I lattice. At temperatures as high as − 50°C the isothermal sequence of transformations I→II→I is capable of producing a substantial degree of purification of ice I in terms of its dielectric relaxation time.

Quantum effects in the dynamics of deeply supercooled water

“…Taking into account the simplicity of the model, these values of a are in a reasonable agreement with the jump length 1.5-1.9 Å found in supercooled water by the quasielastic neutron scattering [82] and NMR [83]. The estimated activation energy ~ 46 kJ/mol is comparable to that found by dielectric spectroscopy in different ices, 44-57 kJ/mol [68][69][70][84][85][86][87]. In spite of the very simplistic and schematic character of our estimate, it shows that the rotational tunneling effects can indeed lead to the experimentally measured value of fragility, m = 14, with the values of the model parameters corresponding to that of supercooled water.…”

“…This result justifies our assignment of the α-process to the structural relaxation in amorphous water. In addition, Figure 5a presents the literature data on relaxation rate in cubic ice I c [68,69] and in hexagonal ice I hex [70]. The activation energy for dielectric relaxation in cubic and hexagonal ices in the temperature range of interest is similar and amount to 44 and 47 kJ/mole, respectively.…”

Evolution with time of the dielectric properties of dispersed ice microcrystals

“…Our interest in the dielectric properties of water-in-oil emulsions and dispersions of ice microcrystals is twofold: it has been proved that a better understanding of the dynamics of water molecules in ice can be achieved by studying different forms of ice [14,15], including dispersions of ice microcrystals [6][7][8][9]. On the other hand, these relatively simple and easy to manipulate systems may serve as models for more complicated systems, such as food emulsions and tissue.…”

“…In this work we study the characteristics of this relaxation at different stages of its evolution with time. The main feature of our approach to the topic is that we discuss the time-induced changes of the characteristics of the dielectric relaxation of water molecules in ice microcrystals in relation to similar effects observed in different forms of ice, such as pure monocrystals [10,11], polycrystalline pure samples [12], polar ice samples [13] and samples with high concentration of imperfections [14,15], and in relation to mechanisms suggested for ice at the molecular level.…”

Ultra-slow relaxation in ice and related substances

“…This may arise from the fact that pressurization of ice induces rejection of ionic impurities from the specimen. 28) Even under such conditions, a residual portion escaped from the segregation acted to enhance the orientational mobility of the water molecules. The rate of spontaneous temperature change was analyzed to derive the enthalpy relaxation time governing the freezing process.…”