Solubility limits of silicate melts

A statistical mechanical model of silica melt is presented in which metal oxides are incorporated into the bonding network. In this approach a Flory-type lattice model for binary silicate melts is coupled with a set of chemical reactions that determine the extent of metal oxide incorporation into the silica network and regulate the distribution of nonbridging oxygens around a central silicon. The theory produces two- and three-phase coexistence curves over a range of parameter space. The three-phase equilibrium regions coalesce to critical end points, where two of the three phases have become critical, and to a nonsymmetric tricritical point, where all three phases have simultaneously become critical. The theory captures the qualitative behavior and essential features of simple binary silicate melts. (C) 1997 American Institute of Physics.