Template formation of magnesium aluminate (MgAl2O4) spinel microplatelets in molten salt

Magnesium aluminate, MgAl2O4 (MA), microplatelets were synthesized using a molten salt technique. α-Alumina platelets partially decomposed from aluminium sulphate were reacted with either commercial magnesium oxide or magnesium nitrate in the molar ratio 1:1 to synthesize spinel platelets. Molten salts such as chloride, MCl (M = Li, Na, and K) and potassium sulphate were used for MA synthesis and the salt to oxide ratio was kept at 3:1 for all compositions. Reactants and molten salt mixes were fired in an alumina crucible for 3 h at from 800 to 1150 °C. XRD revealed complete MA without formation of any secondary phase for powders fired for 3 h at 1100 °C. Electron microscopy revealed the MA platelet morphology and size was the same as the α-alumina platelets indicating a ‘template process’ during molten salt synthesis.