Kinetics of nanocrystalline MgO growth by the sol–gel combustion method

Abstract

Nanocrystalline MgO was synthesized via the sol–gel combustion method using polyvinyl alcohol (PVA) and metal nitrate as precursor. The obtained powders were characterized using infrared absorption spectroscopy (IR), X-ray diffraction (XRD), BET (Brunauer–Emmett–Teller), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The effects of the thermal treatment parameters on the crystallite growth kinetics, crystalline size and specific surface area were investigated. The crystallite size of MgO increases with increasing temperature, whereas the specific surface area decreases with increasing temperature. The activation energy for the crystallite growth was estimated to be approximately 223.7kJ/mol. MgO with crystallite size in range of 13.6nm to 98.7nm and a specific surface area up to 81.54m2g-1 can be produced by controlling the processing parameters. The crystallite size growth during combustion is consistent with grain rotation coalescence, which seems to be related to the loss of external hydroxyl groups, derived from chemisorbed water, in the samples treated at higher combustion temperatures.