Electrical conductivity of molten metal+salt mixtures. Antimony+antimony iodide, bismuth+bismuth bromide, and bismuth+bismuth chloride

Abstract

The electrical conductivities of molten Sb+SbI₃, Bi+BiBr₃ and Bi+BiCl₃ solutions were measured as a functions of temperature for the various compositions (Sb+SbI₃; 0∼4 mole %, 170∼410°C. Bi+BiBr₃; 0∼25 mole %, 230∼480°C. Bi+BiCl₃; 0∼30 mole %, 230∼470°C). The conductivity value (0.1 ohm^–1 cm² mole^–1) of Sb+SbI₃ near 300°C is less by a factor of 1 × 10^–3 than that of the pure bismuth halide melts. At high temperatures the data in salt-rich solutions of Bi+BiX₃ show strong temperature dependence in comparison with those in the pure states. The ionic conduction is interpreted using a new equation related to the concept due to Macedo and Litovitz for the viscosity of liquids. The electronic conduction is discussed in terms of two different conductivity mechanisms. The electronic jumping process proposed by Rice and by Raleigh is adequate only for the very dilute solutions, in view of the localized behaviour of the process. The relation between the intrinsic exchange frequency and the change of entropy due to symmetrization fluctuation is discussed using the two-electron mediated exchange mechanism. The electronic conductivity mechanism, in which scattering by the ions is treated by modification of the Ziman theory concerning the transport properties of liquid metals, can be used to describe conduction over the entire range of composition of systems such as Bi+BiX₃.