Stabilization of mesoporous nanocrystalline zirconia with Laponite

The mesoporous nanocrystalline zircoina was synthesized via solid state reaction-structure directing method in the presence of Laponite. The introduction of Laponite renders the higher thermal stability and lamellar track to the zirconia. Laponite acts as inhibitor for crystal growth and also hard template for the mesostructure. The role of Laponite is attributed to the interaction between the zirconia precursors and the nano-platelets of Laponite via the bridge of hydrophilic segments of surfactant. It results in the formation of Zr-O-Mg-O-Si frameworks in the direction of Laponite layer with the condensation of frameworks during the calcination process, which contributes the higher stability and lamellar structure to the nano-sized zirconia samples

Composition and porosity graded La2−xNiO4+δ (x≥0) interlayers for SOFC: Control of the microstructure via a sol–gel process

We have developed composition and porosity graded La2−xNiO4+δ (x≥0) cathode interlayers for low-temperature solid oxide fuel cell that exhibit good adhesion with the electrolyte, controlled porosity and grain size and good electrochemical behaviour. La2−xNiO4+δ (x≥0) monolayers are elaborated from a derived sol–gel method using nitrate salts, acetylacetone and hexamethylenetetramine in acetic acid. As a function of the organic concentration and the molar ratio of lanthanum to nickel, these layers present platelets or spherical shape grains with a size distribution ranging from 50 to 200 nm, as verified by SEM-FEG. On the basis of this processing protocol, we prepared porosity and composition graded lanthanum nickelates interlayers with effective control of the pore distribution, the nanocrystalline phase, the thickness and the subsequent electrochemical properties

Microstructural and Electrical Features of Yttrium Stabilised Zirconia with ZnO as Sintering Additive

Adding ZnO reduces sintering temperature of yttria stabilized zirconia. Adding up to 0.5 wt% of ZnO is possible to densify to 8 mol% yttria stabilized zirconia (TZ8Y) to 95% of relative density at 1300 °C, besides, the electrical conductivity increases about 30% at 800 °C when compared to pure TZ8Y with the same relative density and average grain size. These results show that TZ8Y co-doped with ZnO can be a potential electrolyte to solid oxide fuel cells and electrolyzer cells

Influence of cosurfactants on the properties of mesostructured materials

The effects of the addition of two different types of cosurfactants, n-alkylamine and n-alkyl alcohol, on he phase behavior of silicate-surfactant mesophases and the pore size of the calcined materials have been investigated using X-ray diffraction, N-2-sorption, TG-MS, and solid state H-1 and C-13 NMR spectroscopy. The cosurfactants were added to a standard room-temperature synthesis, which results in a MCM-41 type, hexagonally ordered material in the absence of cosurfactant. Their addition led either to an increase or a decrease of the pore size and d spacing of the hexagonal mesophase, depending on the nature of the polar headgroup and on the chain length of the cosurfactant. For high cosurfactant/surfactant ratios, however, a transition to a lamellar phase was usually observed. The d spacing and the pore size of the hexagonal mesophase can be decreased considerably down to the supermicropore range by addition of butylamine without a marked decrease in the long- range order of the material. The addition of alcohol, on the other hand, resulted in an increase in the d spacing of the hexagonal phase by up to 3 Angstrom. These results are discussed in terms of differences in the ability of the cosurfactants to interact with the silicate as well as cosurfactant-induced changes in the packing parameter

Influence of cosurfactants on the properties of mesostructured materials

The effects of the addition of two different types of cosurfactants, n-alkylamine and n-alkyl alcohol, on he phase behavior of silicate-surfactant mesophases and the pore size of the calcined materials have been investigated using X-ray diffraction, N-2-sorption, TG-MS, and solid state H-1 and C-13 NMR spectroscopy. The cosurfactants were added to a standard room-temperature synthesis, which results in a MCM-41 type, hexagonally ordered material in the absence of cosurfactant. Their addition led either to an increase or a decrease of the pore size and d spacing of the hexagonal mesophase, depending on the nature of the polar headgroup and on the chain length of the cosurfactant. For high cosurfactant/surfactant ratios, however, a transition to a lamellar phase was usually observed. The d spacing and the pore size of the hexagonal mesophase can be decreased considerably down to the supermicropore range by addition of butylamine without a marked decrease in the long- range order of the material. The addition of alcohol, on the other hand, resulted in an increase in the d spacing of the hexagonal phase by up to 3 Angstrom. These results are discussed in terms of differences in the ability of the cosurfactants to interact with the silicate as well as cosurfactant-induced changes in the packing parameter