Abstract:

The dielectric constant and conductivity of ice doped with different NH3 concentrations are studied by a.c. and d.c. methods at -10, -25 and -40°C. The plots of the real dielectric constant nearly coincide with those for pure ice at -10°C with a static constant εs ≅ 100; a higher divergence is observed at lower temperatures where εs<100 for CI ≥ 5×10-4N. The d.c. and high-frequency conductivities increase with NH3 concentration indicating that the number of ionic and Bjerrum defects is modified by the electrolyte. For CI ≥ 10-3 N, both conductivities are constant, showing that there occurs some phenomenon which limits the concentration of current carriers. The theory of the electrical behaviour of ice is applied and the discrepancy between the behaviour of NH 3- and HF-doped ice is explained by the different values of mobility of defects and of their dissociation from the electrolyte.