Effect of ceria on the properties of yttria-stabilized zirconia-based electrolytic membranes

(ZrO₂)_{1 − x −y}(Y₂O₃)_x(CeO₂)_y (x = 0.08–0.10; y = 0.0–0.01) solid solution crystals were grown by skull melting technique. The effects of CeO₂ addition on the crystal structure and high-temperature conductivity of the crystals have been investigated. According to X-ray absorption near-edge structure spectroscopy, it was found that Ce cations in crystals are present mainly as Ce⁴⁺ ions. The study of the grown crystals by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy showed that all the grown crystals were single-phase and had either a tetragonal t`` or cubic structure, the latter having crystals containing 10 mol% Y₂O₃ and doped with CeO₂. Doping of the crystals with CeO₂ was accompanied by a linear increase in the lattice parameter. This indicates the entry of CeO₂ into the crystal lattice with the formation of a solid solution. The study of the ionic conductivity of crystals by impedance spectroscopy in the temperature range 400–900 °C showed that the substitution of Zr⁴⁺ ions with Ce⁴⁺ ions manifests itself in different ways and can either increase or decrease the value of high-temperature conductivity depending on the content of stabilizing yttrium oxide. Possible reasons for this behavior are discussed.