Synthesis, characterization of monodispersed MgO microspheres and thermal decomposition kinetics of its precusor

Abstract

Monodispersed MgO microspheres were successfully synthesized by a simple solvothermal method using PEG-400 as solvent. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results reveal that the precusor was monoclinic Mg₅(CO₃)₄(OH)₂·4H₂O and composed of nanosheets with the thickness of about 250 nm. By calcining the precusor at 500 °C for 5 min, cubic MgO with similar morphology was obtained. According to the SEM images, it is found that the volume ratio of PEG-400 to deionized water is considered as a crucial factor in the evolution of the morphology. Based on the SEM images obtained under different experimental conditions, a possible growth mechanism which involves self-assembly process was proposed. The thermal decomposition process of MgO precusor was studied by thermogravimetry-differential thermogravimetry (TG-DTG) at different heating rates in air. Thermal analysis kinetics results show that the most probale mechanism models of MgO precusor are An and D3, respectively. In addition, isothermal prediction was studied to quantitatively characterize the thermal decomposition process.

Keywords

PEG-400 / monodisphersed MgO / thermal decomposition kinetics / isothermal prediction

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