The Orientation Polarization in Hexagonal Ice Parallel and Perpendicular to the c-axis

• Published in: Journal of Glaciology
• Main Authors: Johari, G. P., Jones, S. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1978
• Subjects: Earth-Surface Processes; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000033463; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000033463

Abstract The relative permittivity and loss of zone-refined single crystals of hexagonal ice have been measured in the temperature range 200–271 K and frequency range 0.5 HZ–0.2 MHz, using brass, stainless steel, and gold-foil electrodes. The c -axis of the crystal was oriented parallel to the electric field in 14 samples and perpendicular to the field in 8 samples. The equilibrium relative permittivity of orientation polarization ϵ 0 , parallel and perpendicular to the c -axis, is 96.5±1 and the average relaxation time τ a y is 36 μs at 265±0.5K; ϵ 0 = 124±1.5 and τ av = 30 ms, at 210 K. The magnitude of the orientation polarization obeys the Curie-Weiss equation with T 0 = 15±2 K for both the orientations. These values are in contrast with the c. 17% difference in ϵ o for the two orientations reported in the literature. The extrapolated limiting high-frequency relative permittivity ϵ ∞ , measured for both the orientations, is indistinguishable within 0.5%. The logarithmic plot of the product of τ av and temperature against the reciprocal temperature is linear in the range 210–271 K and gives an activation energy and a pre-exponential factor of 51±2 kJ mol –1 and 0.93±0.22 ps K respectively, for both the orientations of the c -axis with respect to the electric field. The decrease in activation energy which has been reported to occur in polycrystalline ice and in single crystal ice near 230 K is not found until a temperature of 210 K. Single crystals of ice stored in the dielectric cell, after the completion of measurements, for periods ranging from 1–11 weeks at 253±2 K showed no change in their ϵ 0 , τ av , ϵ ∞ that could be attributed to the effect of ageing on the orientation polarization.