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In this work the structural evolution of scandium-stabilized zirconia ceramics co-doped with cerium and gadolinium as a function of sintering temperature in the range of 1100–1500 °C was investigated. Two compositions were studied: 1Ce10ScSZ (1 mol.% CeO₂ – 10 mol.% Sc₂O₃ – 89 mol.% ZrO₂) and 0.5Ce0.5Gd10ScSZ (0.5 mol.% CeO₂ – 0.5 mol.% Gd₂O₃ – 10 mol.% Sc₂O₃ – 89 mol.% ZrO₂). X-ray diffraction shows that the initial powders demonstrate a single-phase cubic fluorite structure. Sintering of the Ce–ScSZ ceramics results in partial transformation into a rhombohedral phase at 1100 °C, whereas the Gd–Ce–ScSZ samples retain the cubic phase across all investigated temperatures, demonstrating enhanced structural stability.
The rhombohedral phase formation in Ce–ScSZ ceramics is attributed to residual porosity, which is confirmed by stabilization the cubic phase under reduced heating rate resulting in suppression of porosity. Raman scattering measurements confirm the transformation of phase composition.
The study emphasizes that phase stability in scandium-stabilized zirconia depends not only on dopant type and concentration but also on porosity and powder characteristics. While the rhombohedral phase observed at 1100 °C has limited relevance for dense solid electrolyte membranes in SOFCs, it becomes significant for NiO–ZrO₂(Sc,Ce) anodes, where both ionic conductivity and porosity are required. The findings provide insights into optimizing of powder composition and sintering conditions to achieve stable cubic phases in zirconia-based ceramics, thereby improving their applicability in energy and radiation-hard technologies.
Keywords: scandium-stabilized zirconia, co-doping, cubic–rhombohedral transformation, sintering temperature, XRD, Raman scattering.
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