Aerogel synthesis of yttria-stabilized zirconia by a non-alkoxide sol-gel route

Homogeneous, nanocrystalline powders of yttria-stabilized zirconia (YSZ) were prepared using a non-alkoxide sol-gel method. Monolithic gels, free of precipitation, were prepared by addition of propylene oxide to aqueous solutions of Zr4+ and Y3+ chlorides at room temperature. The gels were dried with supercritical CO2(l), resulting in amorphous aerogels that crystallized into stabilized ZrO2 following calcination at 500 degrees C. The aerogels and resulting crystalline products were characterized using in situ temperature profile X-ray diffraction, Raman spectroscopy, thermal analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption/desorption analysis, and elemental analysis by inductively coupled plasma-atomic emission spectroscopy. TEM and N-2 adsorption/desorption analysis of an aerogel prepared by this method indicated a porous network structure with a high surface area (409 m(2)/g). The crystallized YSZ maintained high surface area (159 m2/g) upon formation of homogeneous, nanoparticles (similar to 10 nm). Ionic conductivity at 1000 degrees C of sintered YSZ (1500 degrees C, 3 h) was 0.13 +/- 0.02 Omega(-1) cm(-1). Activation energies for the conduction processes from 1000 to 550 degrees C and 550-400 degrees C were 0.95 +/- 0.09 and 1.12 +/- 0.05 eV, respectively.