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.

Accelerated discovery of cathode materials with prolonged cycle life for lithium-ion battery

“…A conclusive advantage of the epoxide-mediated technique is that it allows the use of common metal salts as the sol-gel precursors, eliminating the need for highly reactive metal alkoxides. This technique has also proven to be useful in designing the precursor gels of highly homogensous complex oxides [20][21][22][23] . In this study, lithium acetate (CH 3 COOLi), iron nitrate nonahydrate (Fe(NO 3 ) 3 ?9 H 2 O), zirconium chloride (ZrCl 4 ), tetraethyl orthosilicate (Si(OC 2 H 5 ) 4 ) and phosphoric acid (H 3 PO 4 ) were used as the sources of inorganic components, and ethanol was used as the solvent.…”

Synthesis of La9.33Si6O26 Pore–Solid Nanoarchitectures via Epoxide‐Driven Sol–Gel Chemistry

“…It is only recently that aerogel-like materials have been synthesized in electrically conductive, SOFC-relevant compositions and then characterized at operating temperatures. [11,12] An earlier sol-gel route to mixed La-Si oxides modified an acid-catalyzed silica sol-gel method by including lanthanum salts. [13,14] Investigation of a range of hydrolysis rates showed that only very narrow synthesis conditions led to apatite La 9.33 Si 6 O 26 upon calcination (800°C), [1] and impurity phases were common.…”

“…This synthetic protocol is a modification of innovative methods reported by Gash et al for the preparation of transition metal oxide aerogels. [15][16][17] This route was recently extended to mixed transition metal oxide aerogels [11,18] and nanocomposites of silica and metal oxide. [19,20] We obtain gels by mixing tetramethoxysilane (TMOS) into methanolic solutions of LaCl 3 · 6H 2 O and then adding propylene oxide; the gels are processed as described in the Experimental section to form three different pore-solid nanoarchitectures.…”

Development of Non-Siliceous Porous Materials and Emerging Applications

“…59,60 This is partly because of the stable and uniform dispersion of metal cations in the starting solution. Expanding this method, the generation of thermodynamic instability during the epoxide-mediated solgel polymerization enables well-defined macropores to be formed even in mixed oxide systems.…”