DIELECTRIC STUDIES OF THE TRANSITION OF ICE IH TO ICE XI

A voltage-step technique has been used to study the dielectric relaxation of polycrystalline samples of KOH-doped ice above 72 K and during the transformation to ice XI at temperatures below this. The results reveal two relaxation processes which change with the ordering of the ice. The rate of transformation has been studied between 63 and 69 K, and for different samples the rates observed at a given temperature depend inversely on the dielectric relaxation times of the samples above the transition. The permittivity of partially or almost fully transformed ice decreased with decreasing temperature. The observations are discussed in terms of the ordering of bonds by the motion of OH- ions and the need for a domain structure.