Zirconia–Ceria Solid Solution Synthesis and the Temperature–Time–Transformation Diagram for the 1:1 Composition

Publisher Website
Google Scholar
Abstract
Zirconia–ceria solid solutions of tetragonal symmetry (t’ZrO2) containing 30 to 65 mol% ceria were prepared by annealingc′‐ZrO2at 627°C samples sintered at 1660–1760°C, wherec′‐ZrO2is defined as a cubic or tetragonal phase whose axial ratioc/a(tetragonality) is equal to 1. The lattice parameters and the cube root of the unit cell volumes of the annealed samples increased linearly with the ceria content but, on the other hand, the axial ratioc/a(tetragonality) decreased to 1.000 at 70 mol%. During the annealing of each sample, the cell volume decreased because the residual Ce3+ions were oxidized to the smaller Ce4+. The temperature–time–transformation (TTT) diagram of the 1:1 solid solution was investigated for thec′‐t′diffusionless phase transition and thec′–(t + c)diffusional reaction. Thec′–t′transformation was found to behave as a thermally activated process with an activation energy estimated to be 113 kJ/mol. This value may indicate thatc′–t′transformation is controlled by oxygen diffusion accompanied by dimensional changes of the cerium ions.