Transformation, Microstructure Development, and Densification in α‐Fe₂O₃‐Seeded Boehmite‐Derived Alumina

Addition of α‐Fe₂O₃ seed particles to alkoxide‐derived boehmite sols resulted in a 10‐fold increase in isothermal rate constants for the transformation of γ‐ to α‐Al₂O₃. Changes in porosity and surface area with sintering temperature showed no effect of seeding on coarsening of the transition alumina gels, but the 200‐fold decrease in surface area associated with transformation to α‐Al₂O₃ occurred ∼ 100°C lower in seeded gels compared with unseeded materials. As a result of high nucleation frequency and reduced microstructure coarsening, fully transformed seeded alumina retained specific surface areas >22 m²/g and exhibited narrow pore size distributions, permitting development of fully dense, submicrometer α‐Al₂O₃ at ∼ 1200°C.