Contribution to phase equilibria in the Ce2O3 rich part of the Ce2O3–SiO2–ZrO2 system

Four ternary compositions in the Ce2O3 rich part of the Ce2O3–SiO2–ZrO2 system were investigated. The corresponding mixtures of CeO2, SiO2 and ZrO2 were fired at 1400 °C in an Ar + 7% H2 atmosphere until the phase equilibria were attained. The samples were characterized by XRD, SEM and EDS analysis. The thermal effects and the mass changes of the fired compositions were monitored by DTA/TG analyses. The oxyapatite phase, Ce4.67(SiO4)3O, and the fcc phases identified as the solid solutions (CeZr)O2−y, (CezZr1−z)O2−x and Ce2Zr2O7+2δ were observed in this part of the Ce2O3–SiO2–ZrO2 system. The DTA/TGA analyses indicated the presence of the Ce+4 ions in the fired compositions, while the lowest melting temperature was noticed at 1627 °C.