Electrical properties of ice doped with NH3

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 ε_s≅ 100; a higher divergence is observed at lower temperatures where ε_s<100 for C_I 5 × 10^–4 N. 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 C_I 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.