Editors: | F. Kongoli, M. Haumann, P. Wasserscheid, T. Welton, M. Gaune-Escard, A. Angell, A. Riisager |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2018 |
Pages: | 154 pages |
ISBN: | 978-1-987820-86-7 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
There are a very small number of molten halides, which have negative temperature coefficients of electrical conductivity, starting from the salt melting point [1]. We have established [2] that among them are the melts of ZrCl4 and HfCl4, existing only in the narrow (a few tens of degrees) temperature range at high (22-58 atm) pressures of saturated vapors.
According to the only publication on this subject [3], the electrical conductivity of molten InCl<sub>3</sub> also decreases as the temperature increases. This substance melts at 5820 under the vapor pressure of 12 atm, and there is no published data on the critical point of the melt. It is assumed [4] that the structure of molten indium trichloride is intermediate between the molecular configurations of InCl<sub>3</sub>, In<sub>2</sub>Cl<sub>6</sub>, and the network structure of molten YCl<sub>3</sub>-type.
Our experimental data on the electrical conductivity of molten InCl<sub>3</sub>, obtained in a wider temperature range (589-736 °C) than in [3] in a special capillary-type quartz cell with tungsten electrodes, confirm the Klemm's information [3] on the negative temperature coefficient conductivity of the melt, but deviate by 2-7% to the higher values. With a good approximation (R2 > 0.998) our experimental data are represented by the equation:
k = 0.89545 - 3.3764*10-4*T - 2.3178*10-7*T<sub>2</sub> , S/cm; T, K.
The density, molar conductivity, and activation energy of molten InCl<sub>3</sub> were calculated. The reasons for the appearance of negative temperature coefficients of conductivity polytherms of molten salts are discussed.