Synthesis of beta-alumina powders by microwave heating from solution-derived precipitates

The synthesis of beta-alumina powder by microwave heating of the precipitate obtained through solution-precipitate techniques was described. A homogeneous mixture of Al2(SO4)3·18H2O and Na2SO4·10H2O was precipitated by dropping the mixed solution of kaolin-derived aluminum sulfate and sodium hydroxide into ethanol with agitation by stirring. The precipitates were calcined at various temperatures for 1 h under conventional and microwave heating process for obtaining the beta-alumina powder with the structure consisting of β- and β″-alumina phases with a larger amount of β″-alumina phase. The amount of β″-alumina phase in the microwave-calcined samples was larger than that in the conventionally calcined samples.