Na-β′′-aluminas in the ternary system Na2O-Al2O3-MgO(Li2O) were synthesized via a liquid state reaction using MgO and Li2O as stabilizers, and the influence of calcination temperature, precursor pH value, and composition on the phase formation of Na-β′′-aluminas were investigated. For the analysis of the phase fraction of Na-β- and β′′-alumina, the sodium oxide concentration was varied to give molar ratios of [Na2O] : [Al2O3] = 1 : 4, 1 : 5, 1 : 6 and 1 : 8, and the precursor pH was varied from 1.0 to 9.0 by increments of 1.0. The samples were calcined at 1100-1500 oC for 2 hours and characterized by X-ray diffraction, a particle size analyzer, and an SEM. We then compared the phase formation of the Na-β′′-aluminas when the stabilizer MgO was used versus when Li2O was used. The average particle sizes of the synthesized powders were about 300-500 nm.

Keywords: Na+-β´´-alumina, liquid state reaction, transient eutectic liquid.