Formation of TiO2 sols, gels and nanopowders from hydrolysis of Ti(OiPr)4 in AOT reverse micelles

P D Moran; John R Bartlett; G A Bowmaker; J L Woolfrey; R P Cooney

doi:10.1023/A:1008741109896

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Formation of TiO2 sols, gels and nanopowders from hydrolysis of Ti(OiPr)4 in AOT reverse micelles

Journal article

Peer reviewed

Formation of TiO2 sols, gels and nanopowders from hydrolysis of Ti(OiPr)4 in AOT reverse micelles

P D Moran, John R Bartlett, G A Bowmaker, J L Woolfrey and R P Cooney

Journal of Sol-Gel Science and Technology, Vol.15(3), pp.251-262

1999

DOI: https://doi.org/10.1023/A:1008741109896

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Abstract

Materials Engineering

titania nanoparticles

AOT reverse micelles

water-in-oil microemulsions

hydrolysis of titanium alkoxides

Titania sols, gels and nanopowders have been produced by the controlled hydrolysis of tetraisopropyltitanate (TPT) in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. Particle formation and aggregation have been investigated by photon correlation spectroscopy, the crystal phases by FT-Raman spectroscopy, and the crystallite dimensions of the precipitates by transmission electron microscopy. Nanoparticles could be produced at relatively high Ti(IV) concentrations (up to 0.05 mol dm-3). These nanoparticles aggregated into sols, with colloid sizes of 20-300 nm, eventually forming gelatinous precipitates. The kinetics of particle formation and aggregation were controlled by varying the primary process parameters [TPT], [H2O]/[AOT] (w0), and [H2O]/[Ti(IV)] (R), yielding a range of products including stable, transparent sols, precipitates and monolithic gels. The aggregation kinetics and physical properties of the sols depended strongly on w0. Different titania phases were produced, depending on w0; w0 ≤ 6 yielded amorphous particles, while w0 ≥10 produced anatase. The dimensions of the crystallites were comparable to those of the parent reverse micelles. A models was developed to interpret the effect of the primary process parameters on colloidal stability: (1) nucleation to form primary crystallites occurs by rapid hydrolysis and condensation reactions within the reverse micelle and (2) subsequent colloidal growth by aggregation occurs by reverse micellar exchange, where the rate of growth is governed by electrostatic and steric stability factors which increase as [AOT]/[TPT] (S) and residual [H2O]/[AOT] (wr) increase.

Details

Title: Formation of TiO2 sols, gels and nanopowders from hydrolysis of Ti(OiPr)4 in AOT reverse micelles
Authors: P D Moran (Author) - University of Auckland, New Zealand
John R Bartlett (Author) - Australian Nuclear Science and Technology Organisation Materials Division
G A Bowmaker (Author) - University of Auckland, New Zealand
J L Woolfrey (Author) - Australian Nuclear Science and Technology Organisation Materials Division
R P Cooney (Author) - University of Auckland, New Zealand
Publication details: Journal of Sol-Gel Science and Technology, Vol.15(3), pp.251-262
Publisher: Springer New York LLC
Date published: 1999
DOI: 10.1023/A:1008741109896
ISSN: 0928-0707
Organisation Unit: School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99448788902621
Output Type: Journal article

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Collaboration types: Domestic collaboration; International collaboration
Web Of Science research areas: Materials Science, Ceramics