A generalized approach to the flood-knapp structure based model for binary liquid silicates: Application and update for the PbO-SiO2 System |
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Authors: | BO Björkman Gunnar Eriksson Erik Rosén |
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Affiliation: | 1. Department of Inorganic Chemistry, Ume? University, S-901 87, Ume?, Sweden
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Abstract: | The nonideal activity of a metal oxide in a molten binary silicate system is described by treating the liquid as an ideal
solution and by considering the formation of a few complexes. Application of this approach to the binary system PbO-SiO2 shows that the experimentally determined activity of PbO(l) can be modeled by considering the lead silicate melt as an ideal solution of Pb2+ and O2−,SiO
4
4−
, Si2O
7
6−
, Si12O
37
26−
, and Si4O
10
4−
. The calculated Gibbs free energy values for the formation of the anionic complexes from O2− and SiO
4
4−
are: ΔGℴ(Si2O
7
6−
)/J · mol−1 = 38977 − 30.909(T/K); ΔGℴ(Si12O
37
26−
)/J · mol−1 = 200158 − 121.813(T/K); Δℴ(Si4O
10
4−
)/J · mol−1 = 104627 − 28.094(T/K). Values of Gibbs free energy of formation of the solid phases PbO, Pb4Si06, Pb2SiO4, PbSiO3, and SiO2 which, together with the melt model data, give the best fit to experimental phase relations in the system PbO-SiO2 were calculated. These values are all in good agreement with literature data. |
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Keywords: | |
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