Electrical conductivity of biphasic mixtures of molten silver iodide and lithium fluoride, chloride, and bromide

The electrical conductivity (EC) method was used for the biphasic systems of AgI with LiF, LiCl, or LiBr. The difference between the magnitudes of the conductivities for the equilibrium phases of the LiCl+AgI and LiBr+AgI melts decreases with an increase in temperature, becoming zero at 1250 and 983 K. For these temperatures, the values of critical conductivity are kappa (c) = 4.70 S cm(-1) and kappa (c) = 3.90 S cm(-1), respectively. The melt containing lithium fluoride exists in two phases up to a temperature of 1245 K. The temperature dependence of the differences between the conductivities for the coexisting phases is described as an exponential equation, with the critical exponent 0.89. This value is 11% less than that found for alkali halide melts. The covalent bonding between the silver and halide ions can be understood as causing the difference between the critical exponents of the alkali halide melts and those of silver iodide-containing mixtures.