Sol Gel Method

Sulfate–zirconia catalysts were prepared via the colloidal-sol–gel method using ZrOCl2as precursor. After precipitation and washing, the solids were peptized with a 1 : 1 mixture of CH3COOH and H2SO4. The promoters were introduced as gallium, indium, or thallium nitrates into the solution containing the zirconium sols. After a gel formation period, the samples were dried and calcined. The catalysts were

Lithiated layered transitional metal oxide materials of the LiMO2 type and especially LiCoO2 presents interesting specific properties as high energy density, long cycle life and constant discharging properties in a wide range of working conditions as well as a good safety. These properties made these materials excellent candidates as active compounds for high capacity cathode materials for rechargeable lithium batteries. LiCoO2 is the most common lithium storage material for lithium rechargeable batteries, used widely to power portable electronic devices. Operation of lithium rechargeable batteries is dependent on reversible lithium insertion and extraction processes into and from the host materials of lithium storage. In this study, LiCoO2 thin films were prepared by the sol–gel spin coating technique using metal acetate and citric acid as starting materials. Citric acid acts as a chelating agent, which promotes the preliminary reaction between lithium and cobalt and suppresses the precipitation of acetates. The sol–gel method is well known as one of promising thin-film preparation methods, which has good advantages such as low fabrication cost, relatively easy stoichiometry control, high deposition rate and also known as a low-temperature synthesis method for various ceramics. In addition, the crystal phases involved in the thin film can also be controlled by changing the chemical compositions of the sol. The crystallinity, microstructure and electrochemical properties of final films are also studied by XRD, SEM, AFM and galvanostatic charge/discharge cycling test. Films heat-treated under appropriate conditions exhibit high capacity and good crystallinity so those films are considered to be candidates as cathodes for thin-film micro batteries.

Ba(Co,Zn) 2 -W type hexagonal ferrites, prepared by a citrate sol–gel method have been used as fillers in five layers of chlorosulphonated polyethylene matrix composite. Adding an outer layer with carbonyl iron filler, a thin quasi-double-layer microwave absorber has been ...

A colloid-emulsion route is established to prepare yttria stabilized zirconia (YSZ) powder, using cost-effective and commonly available inorganic salts as starting materials. Nanocrystalline, single-phase YSZ powders are prepared via calcinations of emulsion-derived precursor powder at 1000°C for 2 hours. Formation of aggregates is detected, and the aggregates size and morphology depend on the chemical additives nature and milling. After chemical

Using the Rietveld refinement, we analyze the structural evolution under thermal treatment of silica xerogel samples prepared by the sol–gel method with molar ratio (R) of water to TEOS of R = 5 and R = 11.66. We refine the structure of compounds using the Maud program and we found the unit cell parameters and atomic positions of the refined silica amorphous atoms for whole samples. The results show us that the amorphous structure is quartz-like or low-cristobalite-like, depending on the molar ratio values and the heat-treatment of the samples. For R = 5 different quartz structures are obtained, whereas for R = 11.66 we obtain close structures in which a transformation of quartz-like amorphous to low-cristobalite amorphous phase occurs at about 600 °C. These results give some scopes to explain the partial crystallization of the silica at relatively low temperatures obtained when metallic species are present.