The effects of solvent and microwave on the preparation of Magnesium Oxide Precursor

Four methods including hydrothermal method, glycol-hydrothermal method, microwave-hydrothermal method and glycol-microwave-hydrothermal method were used to prepare magnesium oxide precursor by the reaction of MgSO₄·7H₂O with (NH₄)₂CO₃. The composition, crystallinity, morphology, aspect ratio, yield, functional groups, atom distribution, and interplanar spacing of the sample were investigated by X-ray diffraction (XRD), Scan Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and High Resolution Transmission Electron Microscope (HRTEM). The properties of Magnesium Oxide precursor were compared with each other. The results of FT-IR and XRD showed that the crystals were all nesquehonite. However, it was shown by FT-IR results that the crystals prepared by glycol-microwave-hydrothermal method contained OH⁻ and HCO₃⁻ groups, which indicated that the Mg(OH)(HCO₃)·2H₂O type crystals would be facilitated by this method. The glycol-hydrothermal method can create high quality Magnesium Oxide precursor with a high degree of crystallinity, high purity, high aspect ratio, smooth surface, and good dispersibility.