Comparative Study of Yttria-Stabilized Zirconia Synthesis by Co-Precipitation and Solvothermal Methods

Yttria-stabilized zirconia (YSZ) at 8 mol.% is the most commonly used electrolyte material in the solid oxide fuel cell field. In this study, co-precipitation and solvothermal methods are used to synthesize nanocrystalline yttria-stabilized zirconia. The effects of the synthesis condition (calcination temperature) and different methods on the crystal phase, the microstructure and the electrical performance of YSZ are comparatively investigated and analyzed in detail. X-ray diffraction results reveal that both the co-precipitation and solvothermal methods can be used to successfully synthesize nano-YSZ ceramic powders with a pure crystal phase of fluorite cubic structure. The grain sizes of the YSZ samples prepared by these two methods are both smaller than that of the commercial Tosoh YSZ, with the sample from the solvothermal method revealing the smallest grain size. The electrochemical impedance spectra demonstrate that the YSZ prepared by co-precipitation with 500°C calcination reveals the smallest ohmic resistance among different calcination temperatures. It also shows a relatively lower ohmic resistance of 2.04 Ω cm², while the YSZ sample synthesized by the solvothermal method has a higher ohmic resistance of 8.89 Ω cm², with corresponding ionic conductivities of 0.0266 S cm^-1 and 0.00562 S cm^-1, respectively.