Lux-Flood basicity of binary silicate melts Original Research Article

Application of the hybrid polymeric model to depict silicate melt energetics allows to distinguish chemical interaction terms from strain energy contributions. It is thus shown that Lux-Flood basic oxides when admixed with silica in various proportions along simple binaries give rise to purely endothermic effects, while acidic Lux-Flood oxides give rise to athermal mixtures and amphoteric oxides promote both enthalpic and entropic (non-configurational) chemical interactions. The Lux-Flood acid–base character of the various oxides is shown then to be consistent with experimental determinations of nephelauxetic properties of the limiting oxide components in the mean donor ligand field approximation (optical basicity of Duffy and coworkers). The linear proportionality observed between endothermic heat of mixing and optical basicity difference allows to predict the polymerization extent in simple MO–SiO2 molten systems in a wide T range with reasonable precision.