REACTIONS IN SUPERCRITICAL FLUIDS, A NEW ROUTE FOR OXIDE CERAMIC POWDER ELABORATION - SYNTHESIS OF THE SPINEL MGAL2O4

We have performed the decomposition of the alkoxide Mg(Al(OR)4)2, (R ≡ sec-butyl group), in supercritical fluid ethanol. The partly crystallized submicronic powder formed around 350°C and 15MPa leads to the spinel MgAl2O4 after heating at 1200°C. The dried solid particle size ranges from about 0.04 to 0.2μm. The main characteristics of these powders have been compared with those of samples elaborated by sol-gel process. From IR spectroscopic study, a first attempt has been made in order to determine the nature of reactions taking place in the supercritical fluid medium. © 1990.