Emulsion-based synthesis of unaggregated, spherical alpha alumina

Unaggregated spherical α-alumina powder was prepared by the controlled hydrolysis of Al(OPri)3 in a dilute solution consisting of CH3(CH2)6CH2OH and CH3CN. Spherical AlOOH precursors crystallized to γ-alumina at 1000 °C and converted to α-alumina at 1150 °C without intermediate phases. The particle morphology was retained after crystallization to α-alumina. The thermal behavior of spherical AlOOH precursors was characterized by differential thermal analysis (DTA). X-ray diffraction (XRD) was used to confirm the conversion of crystalline phase of alumina powder from amorphous to α-phase. Transmission electron microscopy (TEM) was used to investigate the morphologies and size of the precursors and products. The specific surface areas of α-alumina were measured by nitrogen adsorption technique.