Analysis of disproportionation of Q n structons in the simulation of the structure of melts in the Na2O-SiO2 system

Abstract

A new version of the STRUCTON�1.2 computer program (2009) has been presented. The pro� gram combines the algorithm for calculating real distributions of Q n structons in binary silicate melts (with allowance made for their disproportionation) and the statistical simulation of molecularmass distributions of polymerized ions at different temperatures. This model has been used to perform test calculations for two melts in the Na2 O-SiO 2 system (Na 6 Si 2 O 7 , Na 6 Si 3 O 9 ). The results of the calculations have made it possible to trace variations in the set and concentrations of chain and ring silicon-oxygen complexes with a decrease in the temperature in the order: stochastic molecularmass distribution mole cularmass distribution at T = 2000 K molecularmass distribution at the liqu idus temperature. The main result of these calcula� tions is that the dominant species of silicon-oxygen anions at the liquidus temperatures (in contrast to the stochastic distributions) exactly correspond to the stoichiometry of the initial melts: the chain anions and (SinO3n) 3n- ring complexes are dominant in the Na6Si2O7 and Na6Si3O9 melts, respectively. It has been established that, with a decrease in the temperature, the average size of polymer complexes varies weakly in the Na6 Si 2 O 7 melt but increases by a factor of approximately 1.5 in the metasilicate system.