Thermodynamic simulation of phase equilibria in oxide system FeO-SrO-SiO2

Oxide systems with strontium oxide as one of the main components are used more and more widely in different industries. The effect of adding SrO on slug, flux, and the properties of glass and even ceramic with magnetic behaviour is intensively studied today. However, there is only a limited amount of data on phase diagrams for oxide strontium-bearing systems in academic literature, in particular for triple and multi-component systems. This research involved a thermodynamic simulation of phase equilibria and further construction of phase diagrams for double oxide systems FeO-SrO, FeO-SiO2, SrO-SiO2, and the calculation of coordinates of the liquidus surface projection of the phase diagram for a triple oxide system FeO-SrO-SiO2. The simulation was conducted using the sub-regular ionic solution theory approximation. The study has identified energy parameters of the theory for every of the researched systems. The estimated data on the position of liquidus lines in double oxide systems are comparable to those published in academic literature, thus confirming that the performed simulation is correct. Information on the phase diagram of the triple oxide system FeO-SrO-SiO2 is not presented in the academic literature and have been calculated for the first time. The present paper also analyses the data on the temperatures, enthalpy and entropy of silicate formation Fe2SiO4, Sr3SiO5, Sr2SiO4, SrSiO3 from the components of oxide melt of systems FeO-SiO2 and SrO-SiO2 respectively. For example, in the case of Fe2SiO4, the enthalpy of the compound formation from the components of the oxide melt was 63600 J/mol; in case of the silicate Sr3SiO5 - 181675 J/mol; in case of the compound Sr2SiO4 - 169576 J/mol; and for SrSiO3 - 155697 J/mol.