Mean field theory of fused salts

A new approach to the equation of state of silicate melts: An application of the theory of hard sphere mixtures

“…Longuet-Higgins and Widom (1964) showed that for simple molecular liquids, the structure of liquids is mostly determined by the steeply changing repulsive potential, which can be approximated as the hard sphere potential, whereas the slowly varying attractive potential can be introduced as a uniform negative background potential. This mean field approach was later extended to ionic liquids by Itami and Shimoji (1980) and McBroom and McQuarrie (1983). Following this approach, we consider a silicate liquid as a mixture of hard spheres corresponding to different melt components such as SiO 2 and MgO, and consider the electrostatic energy as a uniformly distributed negative background potential, which does not change the structure of a liquid but will modify the thermodynamic properties of liquids.…”

Thermodynamics of Condensed Ionic Systems

“…The statistical theory for corresponding states for nonelectrolytes (6) arises from the assumption of a universal function for the intermolecular potential scaled with respect to distance and energy. This can also be assumed for an ionic system; indeed the primitive, hard-core model, equation 25, is of that form with a the distance factor and z.zJ· the energy factor.…”

“…Here it is assumed that the structure of the fluid is determined by the sudden repulsive forces and that attractive forces merely contribute a general cohesive·force or mean field. The ionic forces can be shown (24,25) to contribute/ approximately, a term -Acl/3 per particle to the energy or -Ac 4 3 /3 to the pressure. Derivation of A is complex but a simple approximation is The heat of mixing of fused dicated alkali cations as a solution parameter.…”