Colloidal Stability and Titania Precipitate Morphology: Influence of Short-Range Repulsions

Autor: Charles F. Zukoski, J.-L. Look
Rok vydání: 1995
Předmět:
Zdroj: Journal of the American Ceramic Society. 78:21-32
ISSN: 1551-2916
0002-7820
DOI: 10.1111/j.1151-2916.1995.tb08356.x
Popis: For a wide range of reagent concentrations, particles formed from the hydrolysis of tetraethyl orthotitanate in aqueous ethanol solutions fall into two morphological types. In the first, the particles are composed of uniform spheres, while in the second, the precipitate consists of agglomerates of discrete particles which have been fused together by further reaction products. To explain this observation, we develop a growth mechanism where colloidal stability is imparted to the growing particles through a combination of electrostatic and short-range repulsions giving rise to a shallow secondary minimum which develops for certain particle sizes and results in the formation of doublets that can be fused together. If the particle surface potential is of sufficient magnitude, the secondary minimum is no longer accessible by Brownian motion and uniform precipitates result. The effects of particle surface potential and reaction medium ionic strength are discussed.
Databáze: OpenAIRE
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