Estudio termodinamico del sistema SiO₂-NiO-Cu₂O

In this work, the evaluation of the thermodynamic properties and phase diagrams of the NiO-SiO₂, Cu₂O-SiO₂ and SiO₂-NiO-Cu₂O systems is presented in which a structural model is used for the liquid phase. This thermodynamic model is based on the assumption that each metallic oxide produces the depolymerization reaction of silica network with a characteristic Gibbs free energy change. A least squares optimization program permits all available thermodynamic and phase diagram data to be optimized simultaneously for the binary systems. In this manner, data for these binary systems have been analyzed and represented with a small number of parameters. The binary structural model is extended to the ternary system assuming a random mixing of cations Cu⁺ and Ni²⁺, since the Cu₂O-SiO₂ and NiO-SiO₂ binary systems exhibit dissimilar thermodynamic behavior, the SiO₂-NiO-Cu ₂O ternary system is proposed as a tentative phase diagram.