CeO2–YO1.5–NdO1.5 system: An extensive phase relation study

The sub-solidus phase relations in the CeO2–YO1.5–NdO1.5 system have been studied. About 45 compositions in the series Ce1−x(Y0.70Nd0.30)xO2−0.5x, Y1−x(Ce0.50Nd0.50)xO1.5+0.25x and Nd1−x(Ce0.55Y0.45)xO1.5+0.275x were prepared and characterized by powder XRD. In the Ce1−x(Y0.70Nd0.30)xO2−0.5x series, there was a gradual transformation from the defective F-type cubic lattice to an ordered C-type phase with increasing x, whereas in the Y1−x(Ce0.50Nd0.50)xO1.5+0.25x series, the C-type cubic lattice of yttria was retained over the entire range. In the Nd1−x(Ce0.55Y0.45)xO1.5+0.275x system, the compositions with NdO1.5 content greater than 95 mol% showed coexistence of hexagonal, monoclinic and cubic phases. A biphasic region of monoclinic and C-type cubic phases was observed as NdO1.5 decreases from 90 to 70 mol%. All the compositions below 70 mol% NdO1.5, were found to be C-type cubic solid solutions. The phase relations are distinctly characterized by an extensive range of cubic solid solutions, stable under the slow-cooled conditions. To the best of our knowledge, this is the first detailed sub-solidus study reported in CeO2–YO1.5–NdO1.5 system.