Aerogel Synthesis of Yttria-Stabilized Zirconia by a Non-Alkoxide Sol−Gel Route

Abstract

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 °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 N2 adsorption/desorption analysis of an aerogel prepared by this method indicated a porous network structure with a high surface area (409 m2/g). The crystallized YSZ maintained high surface area (159 m2/g) upon formation of homogeneous, nanoparticles (∼10 nm). Ionic conductivity at 1000 °C of sintered YSZ (1500 °C, 3 h) was 0.13 ± 0.02 Ω-1 cm-1. Activation energies for the conduction processes from 1000 to 550 °C and 550−400 °C were 0.95 ± 0.09 and 1.12 ± 0.05 eV, respectively.