A New Method for Synthesis of Fine Crystalline Magnesium Aluminate Spinel

Abstract

A new method for synthesis of high-purity fine crystalline magnesium aluminate spinel (MgAl₂O₄) has been proposed by treating a mixture of finely divided MgO and aluminum hydroxide (Al(OH)₃) or oxyhydroxide (AlOOH) with aqueous fluid under supercritical conditions (T = 380–400°С, Р\(_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}\) = 22.8–23.0 MPa). It has been demonstrated that the formation of the magnesium aluminate spinel structure occurs by a solid state mechanism. The new method of synthesis makes it possible to control the size (from 20 nm to 5 µm) and shape (spherical, lamellar, or bipyramidal) of the synthesized magnesium aluminate spinel (MgAl₂O₄) by varying the reaction conditions.