The effects of temperature and different precursors in the synthesis of nano spinel in KCl molten salt

Abstract

Nano-particles of MgAl 2O 4 were successfully synthesized at 850 °C using the molten-salt method, and the effects of processing parameters, such as the amount and type of precursor and temperature on the crystallization of MgAl 2O 4, were investigated. Spinel nano powders were synthesized by heating stoichiometric compositions of different MgO- and Al 2O 3-bearing precursors in potassium chlorides (KCl). The phase formation, morphology and purity of these powders were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF), respectively. The results demonstrated that the formation of MgAl 2O 4 spinel could be initiated at 850 °C and that, after the temperature was increased to 1000 °C, the amounts of MgAl 2O 4 in the resultant powders increased with a concomitant decrease of MgO and Al 2O 3. Furthermore, the synthesized MgAl 2O 4 grains retained the size and morphology of the Al 2O 3 powders, which indicated that a template formation mechanism dominated the formation of MgAl 2O 4 by molten-salt synthesis.