Sub-solidus phase relations in CeO2–YSZ and ThO2–YSZ systems: XRD, high temperature-XRD and EPMA studies

In the present manuscript, synthesis, XRD, high temperature-XRD as well as electron probe for microanalysis (EPMA) studies on CeO2–YSZ and ThO2–YSZ are being reported. It is found that CeO2–YSZ system shows formation of a cubic solid solution throughout the homogeneity range. The lattice parameter of this cubic solid solution in CeO2–YSZ system decreases linearly on going from CeO2 to YSZ side. On the other hand ThO2–YSZ system was bi-phasic throughout the range. XRD results indicate that YSZ has no solubility in ThO2, however, EPMA studies revealed that a very small amount of YSZ is soluble in ThO2. High Temperature XRD studies were performed on few representative compositions in CeO2–YSZ system and the lattice thermal expansion coefficients (20–1200 °C) of the compositions YSZ, Ce0.2(YSZ)0.8O1.90, Ce0.4(YSZ)0.6O1.925 and Ce0.6(YSZ)0.4O1.950 were observed as 11.32 × 10−6, 11.38 × 10−6, 11.43 × 10−6 and 11.48 × 10−6 °C−1, respectively.