The quaternary system B2O3-PbO-SiO2-ZnO: Thermodynamics and phase diagram

We evaluated the six binary phase diagrams, B₂O₃-PbO, B₂O₃-SiO₂, B₂O₃-ZnO, PbO-SiO2, PbO-ZnO, and SiO₂-ZnO, to obtain a consistent picture for the quaternary system B₂O₃-PbO-SiO₂-ZnO. We used all the available thermodynamic data: enthalpies of mixing, activity data, complete phase diagrams, and miscibility gaps. The agreement between the various sets of data is good. We also calculated the enthalpy of formation of the ternary compound 5PbO-B₂O₃-SiO₂. Δ_fH/R of 1/8 [5PbO-B₂O₃-SiO₂] =-(2.104 ± 0.057) kK.