Diffusion and Relaxation Phenomena in Ice

Abstract

The underlying mechanisms of several rate processes in ice are examined through cross comparisons of the processes with each other and with experimental observations. The assumption that the migration of orientational defects (Bjerrum faults) is the common origin of dielectric and elastic relaxation leads to a predicted ratio of dielectric-to-elastic relaxation time of 32, in close agreement with experiment. The conclusion that a separate process is responsible for diffusion is based on a comparison of diffusion and dielectric relaxation data. The faster diffusive motion controls the thermal equilibration of the proton spins as well as the magnetic resonance linewidths; an interstitial migration appears to be the mostlikely diffusion mechanism.

Investigating hydration dependence of dynamics of confined water: Monolayer, hydration water and Maxwell–Wagner processes

“…37 This study shows that dielectric relaxation does not participate in a FST up to 240 K. A change in fragility should be visible in dielectric relaxation measurements which have been proven to probe reorientational motions better than most other techniques for polar liquids. An inspection of the H diffusivity in ice 38 shows that ice exhibits a very high diffusion rate of water molecules. In fact, the diffusivity of confined amorphous water 5 is closer to that of ice than that of supercooled bulk water.…”

Ab initio investigation of electronic and vibrational contributions to linear and nonlinear dielectric properties of ice

“…(3) is replaced by R 0 , the coefficients in Eqs. (7)- (12) reduce to the pure static electronic term.…”

“…On the contrary, defects seem to have no bearing on the static dielectric properties: their concentration affects the rate at which ice responds to an applied field but not the final value of the polarization. 11,12 The progress of the disorder-order transition in ice can be monitored by dielectric measurements, which can provide an insight into the mechanism whereby such reorganization proceeds. In fact, the low temperature ordering transition of ice Ih to ice XI, induced by doping with KOH, was first studied by this means.…”

Lower-cost, relocatable lunar polar lander and lunar surface sample return probes

“…Studies by Onsager & Runnels [1969], Olhoeft [1998] and oth-ers indicate that water ice deposits, even at low mass fractions (~0.1%), can be robustly discriminated from dry regolith by measuring the dielectric relaxation time constant of the subsurface regolith. Figure 3 illustrates this unique water ice signature as a function of frequency.…”