Application of the Barker lattice theory to modeling of thermodynamic properties of PbO–B2O3–SiO2 melts

The purpose of the present study was to apply the generalized lattice theory of the associated solutions to modeling of thermodynamic properties of melts in the PbO–B2O3–SiO2 system. Values of PbO activity used for simulation were obtained by the high temperature mass spectrometric Knudsen effusion method at the temperature 1100 K for twenty-four compositions in the glass-forming region of the system studied. Thermodynamic data calculated for the PbO–B2O3–SiO2 melts were in agreement no worse than 40% with the experimental ones. In the frame of the model used the relative numbers of bonds of various types as a function of the melt composition were found when the second coordination sphere was taken into account. It allowed to discuss the concentration changes of Gibbs energy of formation in the melts considered in relation to the formation of various types of chemical bonds. Thermodynamic functions in PbO–B2O3–SiO2 melts found in the present study were compared also with the corresponding data calculated using the semi-empirical Kohler method using the data for the binary systems.