The effects of processing parameters on formation of nano-spinel (MgAl2O4) from LiCl moltensalt

Nano-MgAl2O4 particles were successfully synthesized at 850 °C using the molten-salt method, and the effects of processing parameters, such as temperature, holding time and amount of salt on the crystallization of MgAl2O4 were investigated. Nano-alumina, magnesia and lithium chloride were used as starting materials. LiCl molten salt provided a liquid medium for reaction of Al2O3 and MgO to form MgAl2O4. The results demonstrated that MgAl2O4 started to form at about 650 °C and that, after the temperature was increased to 1000 °C, the amounts of MgAl2O4 in the resultant powders increased with a concomitant decrease in Al2O3 and MgO contents. After washing with hot-distilled water, the samples heated for 3 h at 850 °C were single-phase MgAl2O4 with 30-50 nm particle size. Furthermore, the synthesized MgAl2O4 particles retained the size and morphology of the Al2O3 powders, which indicated that a template formation mechanism dominated the formation of MgAl2O4 by molten-salt method.