Interface in Immiscible Ionic Melts

The results of studying the properties of the interfacial layer in immiscible mixtures LiF + KBr, LiF + CsCl, LiF + RbBr, LiF + KI, LiF + CsBr, LiF + RbI, LiF + CsI, LiCl + AgBr, LiCl + AgI, and NaCl + AgI are summarized. The interfacial layer thickness is found to increase with temperature and to tend toward infinity near the critical mixing temperature. At the same temperature and ion size ratio, the interfacial layer thickness in the melts containing silver halides turns out to be lower than that in the mixtures of alkali metal halides. The surface formation energy for the mixtures of alkali metal halides decreases when temperature increases, obeying a power equation with a critical exponent of 1.5 in the vicinity of the critical mixing temperature. The critical exponent of the Galvani potential for the mixtures containing silver halide turns out to be 18% lower than the critical exponent of the interfacial tension, which is related to the peculiarities of the chemical bond of silver halides. At the same temperature, an increase in the difference between the mixed-ion sizes is shown to cause an increase in the energy and a decrease in the diffusivity of the transition layer because of a decrease in the mutual solubility of the components in this direction.