Self-Propagating High-Temperature Synthesis of Magnesium Aluminate Spinel Using Mg-Al Alloy

In this study, magnesium aluminate spinel (MgAl₂O₄) was synthesized by a self-propagating high-temperature synthesis method using Mg-Al alloy with a Mg/Al mass ratio of 50:50 as raw material. Synthesized MgAl₂O₄ was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, UV-vis diffused reflectance spectroscopy, photoluminescence, and thermogravimetric differential scanning calorimetry techniques. The results show that synthesized products are of high purity and excellent crystallinity. However, the particle size is not uniform and there is obvious agglomeration. The crystallite size of spinel phase is calculated to be 37.78 nm. In the UV band, the synthesized MgAl₂O₄ has a certain absorption capacity, and the extrapolated band gap is 4.02 eV. The synthesis mechanism was studied, and continued rupture and growth of the oxidation layer is thought to be responsible for grain refinement.