Effect of Precipitation Acidity on the Structure and Morphology of α-Al2O3 Powder Particles
摘要
Abstract
The effect of the solution acidity on the phase composition and morphology of alumina powers precipitated from solution using Al(NO3)3·9H2O and NH4HCO3 was studied. In the рН range of 5–7, an amorphous precursor powder was typically formed; at рН 8–9, NH4AlCO3(OH)2 crystals were formed. When annealed, the powders precipitated from acidic solutions were 100% α-Al2O3, which was represented by agglomerated equiaxed particles sized ca. 100–200 nm. The powders prepared in neutral or alkaline solutions, when annealed, formed additional minor θ-Al2O3 and γ-Al2O3 phases in equiaxed particles sized ca. 20–25 nm.