Preparation of Spherical Scandium Oxide Powders by Ammonium Bicarbonate Precipitation

Abstract:

The preparation of spherical scandium oxide powders by ammonium bicarbonate precipitation was investigated. The carbonate containing scandium was prepared in the solution with ScCl₃·XH₂O as precursor. The effect of reaction temperature, amount of precipitant and stirring speed on the recovery of scandium was discussed. The effect of pH on the crystalline structure and particle size of carbonate containing scandium was characterized by the powder X-ray diffraction and laser particle sizer. Results demonstrate that the structure of carbonate containing scandium changes from non-crystalline structure to crystalline structure with increasing the reaction pH value. It indicates that when the initial change pH value is about 6, the crystalline structure of scandium oxide is cubic structure. Meanwhile, scandium sediment particles with 3.756?103.8 μm in size can be obtained in a certain condition, depending on the pH value,. When the feasible pH value is 7, the D₅₀ of scandium sediment can be 6.634 μm. The carbonate containing scandium is used as a precursor for the preparation of scandium oxide. The TG-DTA result indicates that the decomposition temperature of the carbonate tends to about 600 ℃. Based on the XRD and IR analysis, it can be concluded that the appropriate calcination temperature for obtained relatively pure scandium oxide is 1000 ℃. Meanwhile, the obtained scandium oxide powders were characterized by the laser particle size analyzer, BET and SEM-EDS. The crystallite size of spherical scandium oxide powders is less than 10 μm with a surface area of about 373.952 m²/g. The microstructure is very homogeneous with spherical structure.