An Interacting Pair Model for Alkaline Binary and Ternary Liquid Silicates: Application to the Systems Na(3)O-K(2)O-SiO(2) and Na(2)O-Cs(2)O-SiO(2)

Among all the available models describing the structure of molten silicates, that of Pelton el al. allows accurate fitting of the experimental data of the free energies in the binary systems MO-SiO(2) with M = Fe, Mn, Pb, and Ca. An extension to the ternary systems MO-MʹO-SiO(2), where M and Mʹ are alkaline metals, is proposed. A statistical treatment of the configurations of the solution gives a meaning to the new parameters. The mixed alkaline effect is quite well shown by the application of the model to the ternary systems K(2)O-Na(2)O-SiO(2) and Cs(2)O-Na(2)O-SiO(2),, in particular, in the calculation of the configurational entropy.