Ternary phase relations in CeO2–DyO1.5–ZrO2 system

The present work explores the sub-solidus phase relations in the CeO2–DyO1.5–ZrO2 ternary system. About 80 compositions in Zr1−xDyxO2−x/2, Ce1−xDyxO2−x/2, (Ce0.8Zr0.2)1−xDyxO2−x/2, Zr1−x(Ce0.2Dy0.8)xO2−0.4x, Cex(Dy0.5Zr0.5)1−xO1.75+x/4 systems, were synthesized and explored to investigate the phase fields in this ternary system. Detailed XRD analysis showed the existence of a variety of phase fields viz. Fluorite-type cubic, C-type cubic, biphasic fields containing both F-type and C-type phases as well as co-existence of two different fluorite type phases. A few compositions also showed the presence of monoclinic as well the tetragonal phases. The trends observed in cell parameter are found to be governed by the competing factors of average ionic radius and the repulsion between excess anions in the lattice due to the aliovalent substitution. This ternary system showed the existence of a very wide cubic phase field. This ternary phase relation has relevance to the inert matrix fuel concept.