Microwave idrothermal synthesis of magnesium-aluminium spinel

Abstract Magnesium–aluminium spinel powder was prepared by microwave hydrothermal synthesis method. The phase structure of the samples was analysed using X-ray diffractometer. The microscopic morphology of the samples was analysed by scanning electron microscope. The particle size of the powder was characterised. The effects of different microwave hydrothermal reaction temperatures on the phase structure, micromorphology and particle size distribution of the precursors were studied. Results show that when hydrothermal reaction temperature was controlled at 140 °C-180 °C, pure magnesium–aluminium composite hydroxyl-hydrate precursor can be obtained after 200 min. The median diameter of magnesium–aluminium spinel precursor powder under 150 °C was 5.958 μm, which is the minimum. After calcination, the morphology of the powder underwent a process from flaking and particle stacking to development of complete flake morphology as the microwave hydrothermal reaction temperature increased. The agglomeration phenomenon was very serious when the synthesis temperature was greater than 150 °C.