Conductivity of molten mixtures KF-NaF-AlF₃ is measured in the whole concentration range of the [NaF]/([KF] + [NaF]) ratio at the cryolite ratio CR = 1.3 and 1.5 in the temperature range from 800°C to liquidus temperature. Replacement of K⁺ cations by Na⁺ ones results in a considerable conductivity increase. Alumina solubility rises with temperature and cryolite ratio ([KF] + [NaF])/[AlF₃] in the KF-NaF-AlF₃ system, and decreases with sodium fluoride content. Regression equations obtained allow calculating alumina solubility and electrical conductivity in the KF-NaF-AlF₃ system in the CR range from 1.3 to 3.0 depending on the concentration of the components and temperature.

Recent developments in the field of low-temperature electrolytes and electrolysis are considered. Although the investigations have not found fundamental problems in low-temperature aluminum electrolysis development as an industrial process, challenges remain in cell design, construction, and operation of cells with these emerging technologies.

The temperature dependences of the dynamic viscosity of molten lithium and beryllium fluorides, which are considered as candidate compositions for fuel and