Electrical Conductivity and Thermopower of Metal Ammonia Solutions

Abstract

Data of equivalent conductivity of sodium ammonia solutions in a wide concentration, temperature and pressure range prove that the nonmetal‐metal transition is favoured by increasing temperature and disfavoured by increasing pressure. Some data on the temperature dependence of the thermopower support the concept of activated transport (semiconduction) in the transition range, although the combination of thermopower and conductivity data does not follow the simple theory of semiconductors. In conclusion it is shown that the conductivity behaviour of metal ammonia solutions can be explained by a homogeneous chemical equilibrium between solvated electrons (electrolytic conduction) and free electrons (metallic conduction) which as usually depends on concentration, temperature and pressure.

Thermoelectric Power Generation in a Vacuum Cell of Decomposing Liquid Potassium-Ammonia Solutions

“…K-NH 3 solutions are well known to undergo much more violent and rapid decomposition on heating; however, they generate higher thermoelectric power compared to Li-NH 3 solutions [9][10][11][12] or Na-NH 3 solutions [13,14]. The dissolution process in K-NH 3 solutions results in the potassium's valence electron being spontaneously ionized into a solvent.…”

“…Recently, with the growth of high-tech equipment, many developments have been achieved such that the material structures of these solutions and the distribution of electrons, conductivities and distances between atoms have been measured [1][2][3][4][5][6]. Ever since Dewald and Lepoutre [7] announced the thermoelectric phenomenon in 1953, various thermoelectric experiments on these solutions have been recognized [8][9][10][11][12][13][14][15][16][17]. Nevertheless, because thermoelectric experiments on these solutions have to be carried out under restricted conditions, it is very hard to determine the accurate values for the thermoelectric power of these solutions, indispensable in the analysis of the electronic conduction mechanism [8][9][10][11][12][13].…”

“…For this reason, the preparation and decomposition of K-NH 3 solutions is much more difficult than those of Li-NH 3 or Na-NH 3 solutions. Hahne et al [14], Damay et al [15] and Niibe et al [16] have reported the thermoelectric experimental results of these solutions in the temperature range from −65 °C to −50 °C. Unfortunately, these thermoelectric experimental data are not in agreement with each other and thus, are not available and reliable.…”