CITRATE SOL-GEL METHOD FOR THE PREPARATION OF BETA BETA''-ALUMINA

The concentrations of hydroxide and citrate for sodium, lithium and aluminum ions in an aqueous solution have been theoretically calculated with respect to pH, and their solubility diagram was obtained. The stoichiometric beta/beta'' -alumina with the formula Al11-x/2Lix/2O17Na1+x (x = 0.6) could be prepared from the homogeneous citrate precursors at pH almost-equal-to 6.5. The sol-gel system with Na-Li-Al-C6H8O7-H2O proved to be quite appropriate for achieving the uniform mixing of the reactants on a molecular level by the formation of the m-Al2O3 phase.