Synthesis of Nanocrystalline MgAl2O4 Spinel Powder by Microwave Assisted Combustion

Microwave assisted combustion can be regarded as an effective and economic method for preparation of some inorganic functional materials. In this paper, nanocrystalline MgAl2O4 spinel powders were prepared with the mixture of magnesium nitrate, aluminum nitrate and urea as fuel. Morphology structure of the powders and particle size distribution were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Thermo-Gravimetric/Differential Thermal Analyzer (TG/DTA), respectively. Microwave processing generates a mass of uniform heat in a short time. The gas created during the combustion improves the dispersion of the power and accelerates the formation of the nano crystalline. It is shown that nano crystalline MgAl2O4 spineling powders of narrow particle size distribution and completely crystallized can be prepared when the power is 640 W. Sinter can promote the grain growth of MgAl2O4 spinel. When sintered at 1500 degrees C, the grain has exhibited octahedral structure.