Chemical synthesis of magnesium aluminate spinel powders: A comparative study of the sol-gel and self-combustion routes

Magnesium Aluminate Spinel powders have been synthesized using sol-gel and self-combustion routes. The sol-gel powder was obtained using Mg(NO3)2 and aluminum tri-secbutoxide as the cation sources dissolved in isopropanol to obtain a gel that was calcined from 400 to 1100 degrees C to elucidate its thermal evolution. Besides, the self-combustion route was selected as a simple and time-saving method. In the later, a so-called Deep Eutectic Solvent (DES) was prepared using Mg(NO3)2, Al(NO3)3, and urea as the fuel. The DES was introduced in a furnace pre-heated at 400 degrees C and up to 1100 degrees C to evaluate the evolution of the spinel phase. Self-combustion powders are closer to stoichiometry and crystallize at a lower temperature (600 degrees C) than those obtained by the sol-gel route. These changes were attributed to the exothermic nature of the self-combustion reaction. Upon firing at 1100 degrees C, both methods lead to submicron particles consisting of nanocrystalline grains of less than 40 nm.Graphical abstractChemical synthesis by self-combustion and sol-gel routes produced highly crystalline magnesium aluminate spinel powders, upon firing at 1100 degrees C, the two powder particles grow to the submicrometer size range