Hard-sphere model of fused salts

Abstract

The hard-sphere model has been applied to simple fused salts by taking into account the effect of cohesive energy as a uniform negative background potential which is inversely proportional to one-third of the volume. The temperature dependence of the hard-sphere diameter is also taken into account. By the use of such an improved hard-sphere model, it is possible to predict self-consistently entropy and heat capacity values of fused salts in reasonable agreement with experimental results. The hard-sphere diameter derived in this way is very close to the distance of the first maximum in the experimental pair correlation function of fused salts. This is in marked contrast to earlier results for similar calculations based on simple hard-sphere models such as the scaled-particle theory, in which the diameters obtained were close to those in the gaseous phase. Moreover, it is shown that the self-diffusion coefficients of fused salts calculated from the same point of view are in good agreement with experimental values; calculated values of viscosity coefficients are, however, about half those of experimental results.