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Microstructure evolution in chelated partially hydrolysed alumina sols during sonogelling

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Title Microstructure evolution in chelated partially hydrolysed alumina sols during sonogelling
 
Creator HARIDAS, MM
BELLARE, JR
 
Subject gel synthesis
alkoxides
precursor
chemistry
ceramics
sol-gel
microstructure
alkoxide
chelate
cryo-sem
agglomerate
nano-alumina
evolution
viscosity
qels
 
Description Optically transparent alumina sonogels with optical transmittance of over 90% have been prepared by chemically modifying a partially hydrolysed aluminium sec-butoxide precursor with ethyl acetoacetate. Chelating the alkoxide in a 1:2 molar ratio has permitted an enhanced control over microstructural changes during the sol to sonogel synthesis. Particle size and morphology changes during controlled sonogelling indicate that the sol to sonogel evolution in chelated alkoxides occurs by a dissolution-nucleation process in which the chelated species dissolves and aluminium hydroxide nucleates. The chelated agglomerates break down with increasing amount of water, and finally dissolve into the alcohol rich medium. The breakdown of chelated agglomerates is accompanied by the formation of nanosized aluminium hydroxide particles which grow with water addition into aggregated micron sized, spherical species. The chelated agglomerates evolve from a spherical geometry to a cylindrical morphology to a tapelike structure with a preferred orientation, and finally to a wavy sheet-like matrix. The nano-aluminium hydroxide particles increase in size at every water addition and grow to about 1 mu m at the sonogel point.
 
Publisher INDIAN ACADEMY SCIENCES
 
Date 2011-08-02T04:52:20Z
2011-12-26T12:53:42Z
2011-12-27T05:40:38Z
2011-08-02T04:52:20Z
2011-12-26T12:53:42Z
2011-12-27T05:40:38Z
1997
 
Type Article
 
Identifier BULLETIN OF MATERIALS SCIENCE, 20(1), 49-66
0250-4707
http://dspace.library.iitb.ac.in/xmlui/handle/10054/8666
http://hdl.handle.net/10054/8666
 
Language en