High-Temperature Synthesis of Materials: Glycothermal Synthesis of Alpha Aluminum Oxide

A technology for the glycothermal synthesis of α-Al₂O₃ particles of controlled size and shape has been developed. This technique allows for the production of anisometrically shaped particles with controlled morphology and size distribution. Morphological control of particle shape is described as a function of reaction conditions in which platelet morphologies are produced at high shear rates and polyhedra are formed at low shear rates. Particle size control is also investigated via the use of seed materials which promote epitaxial growth, thereby reducing the surface energy contribution to the nucleation barrier. α-Al₂O₃ seed materials can be used to form particle sizes as small as 100-200 nm without agglomeration. α-Fe₂O₃ seeds have similar effects in comparison with the α-Al₂O₃ seeds, but require higher values of seed number concentration to achieve equivalent particle size effects. Morphological control is unaffected by seeding additions.