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Effect of Hydrothermal Conditions on the Morphology of Colloidal Boehmite Particles: Implications for Fibril Formation and Monodispersity
Author(s) -
Buining Paul A.,
Pathmamanoharan Chellappah,
Bosboom Monique,
Jansen J. Ben H.,
Lekkerkerker Hendrik N. W.
Publication year - 1990
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1990.tb07602.x
Subject(s) - boehmite , dispersity , materials science , morphology (biology) , hydrothermal synthesis , hydrothermal circulation , crystallite , colloid , molar ratio , chemical engineering , yield (engineering) , aluminium , crystallography , mineralogy , chemistry , catalysis , polymer chemistry , composite material , organic chemistry , metallurgy , biology , genetics , engineering
The synthesis of colloidal boehmite (AlOOH) is studied by heating basic aluminum chloride solutions under constant stirring. The temperature and Al 2 O 3 : Cl molar ratio influence the product morphology. Synthesis at 140°C generates highly fibrous polycrystalline particles that are on average 360 nm long, 30 nm broad, and 8 nm thick. They contain 0.11 mol of excess H 2 O per 1 mol of AlOOH. Synthesis at temperatures between 140° and 190°C produces broader fibrils and less excess H 2 O. Preparation at 220°C eventually produces fully crystalline platelike boehmite particles about 260 nm long, 95 nm broad, and 14 nm thick, without excess H 2 O. Fibril synthesis requires an Al 2 O 3 :Cl molar ratio exceeding 1.0 to yield noncoagulated particles. The fibrils are fairly monodisperse with 20% standard deviation in their length for an Al 2 O 3 : Cl molar ratio about 1.0.