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Abstract Despite YSZ being a mature ceramic system, powder-level control of phase composition, crystallite size, surface chemistry, and pore hierarchy remains decisive for current processing routes and applications (e.g., electrolyte and electrode fabrication, thermal spray feedstock conditioning, and functional coatings). Powders of ZrO₂ stabilized with 3, 9, or 12 mol% Y₂O₃ (YSZ) were synthesized by a controlled sol–gel route and characterized after drying at 100 °C and calcination at 500 °C by field-emission scanning electron microscopy, N₂ adsorption, Fourier-transform infrared spectroscopy, X-ray diffractometry (XRD; including Rietveld refinement), and thermogravimetry (TG)-differential scanning calorimetry (DSC) coupled to mass spectrometry (MS). Drying at 100 °C yields predominantly microporous powders with high surface areas that decrease markedly with yttria content (Specific surface area, SSA ≈ 219, 108, and 98 m²·g⁻¹ for 3YSZ-100, 9YSZ-100, and 12YSZ-100, respectively), whereas calcination at 500 °C produces a micro-to-mesopore transition with strongly reduced porous development (SSA ≈ 35, 35, and 22 m²·g⁻¹ for 3YSZ-500, 9YSZ-500, and 12YSZ-500). XRD confirms amorphous character at 100 °C and crystallization at 500 °C, with 3YSZ-500 containing a mixed tetragonal/cubic assemblage (66.8/33.2 wt%) while 9YSZ-500 and 12YSZ-500 are cubic; crystallite sizes decrease from ~12 to ~6–7 nm as Y₂O₃-doping increases. TG-DSC-MS identifies dopant-dependent decomposition/oxidation events (CO₂ evolution near ~315 °C and ~480 °C) that rationalize the transition from an organics-containing amorphous network to a crystalline oxide lattice and the attendant collapse of microporosity. These results provide a composition-resolved correlation between pore hierarchy, crystallization/phase assemblage, and thermal decomposition pathways under identical sol–gel processing conditions.
Díaz-Parralejo et al. (Fri,) studied this question.