Low Temperature Molten Salt Synthesis of Nano Crystalline MgAl2O4

Abstract

MgAl2O4 (MA) spinel nano powder was synthesized using a molten salt technique, by heating stochiometric composition of MgO and AlOOH. NaCl salt was used as reactor media for MA spinel formation. Reactants and molten salt mixtures were fired in an alumina crucible for 3 h at temperature ranges from 850 oC to 1000 oC. The synthesis temperature was decreased from 1300 oC required by the conventional solid–solid reaction process to 850 oC for molten salt approach. The synthesized powders were characterized by X-ray diffraction pattern (XRD), scaning electron microscopy (SEM) and Brunauer-Emmett-Teller technique (BET). XRD revealed complete formation of MA without remaining of any secondary phase for synthesized powder fired at 850 oC for 3 h. Moreover, electron microscopy illustrated that the MA morphology and size was the same as the nano boehmite morphology which confirmed the existence of a ‘template process’ mechanism during the molten salt synthesis. In addition, high surface area for nano MA powders was achieved in this method.