Phase equilibrium relations in the specific region of CaO-SiO2-La2O3 system

The blank of phase equilibrium relations, liquidus, and other information in the CaO-SiO2-La2O3 basic slag system phase diagram limits the application of rare earth elements in the smelting, processing, and high temperature materials. In the current work, phase equilibrium relations in the CaO-SiO2-La2O3 system at 1373 K–1873 K were studied experimentally by using thermodynamic equilibrium experiment followed by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). According to the experimental data, primary crystal field of SiO2, La2O3·2SiO2, CaO·3SiO2·2La2O3, and 2CaO·SiO2 were identified respectively. The 1473 K–1873 K liquidus lines in SiO2 primary crystal field and 1373 K–1873 K liquidus lines in CaO·3SiO2·2La2O3 primary crystal field were also determined. Sub-solidus phase fields in the ternary system were identified, and then the reaction type and temperature range of relevant invariant points were determined. Finally, the CaO-SiO2-La2O3 ternary system phase diagram within specific region was obtained.