Ferromagnetism and diamagnetism behaviors of MgO synthesized via thermal decomposition method

MgO powders were synthesized by a thermal decomposition method which was determined by differential scanning calorimetry coupled with thermogravimetric analysis (TG/DSC). The starting material, Mg(OH)2, was calcined at 400 °C, 450 °C and 500 °C for 1 h each to obtain the MgO powders. Phase composition, morphology and magnetic properties at room temperature of calcined powders were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fourier transform infrared Spectroscopy (FTIR) and vibrating sample magnetometer (VSM), respectively. Both Mg(OH)2 and MgO phases were found in all calcined powders. The combination of ferromagnetism and diamagnetism at room temperature of all powders were observed. It is believed to be attributed to Mg vacancies and defect in the MgO and Mg(OH)2 structures. •Series of thermal decomposition of Mg(OH)2 experiments were carried out.•Different levels of crystallinity/vacancy of MgO were systematically achieved.•Root causes of ferromagnetism and diamagnetism were investigated.•Rietveld analysis and site occupancy factor were used to determine the vacancies.•Additional FTIR and PL experiments were performed.