Revised Phase Diagram of the System ZrO₂‐CeO₂ Below 1400°C

Abstract

The phase diagram of the system ZrOz-CeOz was reinvestigated using hydrothermal techniques. Cubic, tetragonal, and monoclinic solid solutions are present in this system. The tetragonal solid solution decomposes to monoclinic and cubic solid solutions by a eutectoid reaction at 105Oo+5O0C. The solubility limits of the tetragonal and cubic solid solutions are about 18 and 70 mol% CeOZ, respectively, at 14OO0C, and about 16 and 80 mol% Ce02, respectively, at 12OO0C. Solubility limits of the monoclinic and cubic solid solutions are about 1.5 and 88 mol% CeOz at 1000°C, and 1.5 and 98 mol% CeOz at 800°C, respectively. The compound Ce2Zr,010 is not found in this system.

TEM Observation of Reaction at the Interface between Yttria-Doped Ceria and Yttria-Stabilized Zirconia

“…Other oxide-doped CeO -ZrO systems are expected to follow this basic phase transition behavior, though the stability of each fluorite phase is influenced by the kind of dopants. Yoshimura et al (5)(6)(7)(8) have explained phase equilibria in the system ZrO -CeO and established metastable-stable phase diagrams. The transport properties of oxide ion strongly depend on the mixing of cerium and zirconium ions as well as dopant concentration of aliovalent cations such as Ca or Y (9, 10).…”

Structure and Phase Diagram of ZrO<SUB>2</SUB>&ndash;CeO<SUB>2</SUB> Ceramics

“…al. (14) or by the present authors that the supercooled cubic phase decomposes into the equilibrium cubic and tetragonal phases by annealing, leading to the splitting of the XRD lines of the cubic phase.…”

Preparation and characterization of ZrO2/CeO2 ceramic composite synthesized by microwave combustion method

“…The added Ce 3+ enter the zirconia lattice partially substituting the Zr 4+ , either by reducing the free energy of the tetragonal phase or increasing the constraints on phase transformation 45 . The presence of the monoclinic phase in mixtures containing 5 and 12 mole % of CeO 2 at high temperature is due to the increase in the grain size that enhanced the transformation of the tetragonal to the monoclinic phase 46,47 . The transformable tetragonal phase (t) takes place at a critical crystallite size of ~ 22 nm to the monoclinic phase as seen in Table 1. According to pervious work, fracture toughness and strength increase with increasing in the amount of transformable tetragonal phase in the ceramic and thereafter decrease in transformable tetragonal phase and increase in non transformable tetragonal phase with further increase in ceria concentration.…”