Dielectric properties of single crystals of HCl-doped ice

Dielectric properties of single crystals of HCl-doped ice were measured in a frequency range 5×10−4 to 1×105 Hz and temperature range −10 to −150 °C. High-frequency and dc conductivities, σ∞ and σ0, and relaxation times of the Debye and low-frequency dispersions, τD and τL, showed changes of temperature dependencies at a temperature Tc. Values of σ0 at temperatures above Tc were constant, implying the complete dissociation of HCl molecules producing H3O+ ions in the ice lattice, so that σ0 is proportional to the HCl concentration (nHCl). At temperatures below Tc, both of σ∞ and σ0 were found to vary with the square root of nHCl. The behavior of σ0 is in good agreement with earlier results, but that of σ∞ is not. The result suggests that L defects can be liberated from HCl molecules through some activation process in the crystal lattice of ice.