Determination of the shape, size and porosity of fine α-Al2O3 powders prepared by emulsion evaporation

Stable water in oil emulsions were prepared from Al(NO3)3 solutions of different molarities. Dark brown precursors were obtained from these emulsions which were evaporated by adding them dropwise into hot mineral oil. The precursors containing diaspore as raw alumina were calcined at 1000 °C and fine α-Al2O3 powders were obtained. The photographs of the powders were taken by the use of an electron microscope and their particle size distributions were determined. The shapes and sizes of the powders were discussed. Their mesopore size distributions were obtained from the data of the desorption of nitrogen at 77 K. The relation between the obtained results and the concentrations of the Al(NO3)3 solutions were discussed.