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Effect of Gas Flow Rates on the Anatase–Rutile Transformation Temperature of Nanocrystalline TiO2 Synthesised by Chemical Vapour Synthesis

Imteyaz Ahmad, Md. and Bhattacharya, S. S. and Fasel, Claudia and Hahn, Horst (2009):
Effect of Gas Flow Rates on the Anatase–Rutile Transformation Temperature of Nanocrystalline TiO2 Synthesised by Chemical Vapour Synthesis.
In: Journal of Nanoscience and Nanotechnology, ASP, pp. 5572-5577, 9, (9), ISSN 15334880,
[Online-Edition: http://dx.doi.org/10.1166/jnn.2009.1110],
[Article]

Abstract

Of the three crystallographic allotropes of nanocrystalline titania (rutile, anatase and brookite), anatase exhibits the greatest potential for a variety of applications, especially in the area of catalysis and sensors. However, with rutile being thermodynamically the most stable phase, anatase tends to transform into rutile on heating to temperatures in the range of 500 °C to 700 °C. Efforts made to stabilize the anatase phase at higher temperatures by doping with metal oxides suffer from the problems of having a large amorphous content on synthesis as well as the formation of secondary impurity phases on doping. Recent studies have suggested that the as-synthesised phase composition, crystallite size, initial surface area and processing conditions greatly influence the anatase to rutile transformation temperature. In this study nanocrystalline titania was synthesised in the anatase form by a chemical vapour synthesis (CVS) method using titanium tetra iso-propoxide (TTIP) as a precursor under varying flow rates of oxygen and helium. The anatase to rutile transformation was studied using high temperature X-ray diffraction (HTXRD) and simultaneous thermogravimetric analysis (STA), followed by transmission electron microscopy (TEM). It was demonstrated that the anatase-rutile transformation temperatures were dependent on the oxygen to helium flow rate ratio during CVS and the results are presented and discussed.

Item Type: Article
Erschienen: 2009
Creators: Imteyaz Ahmad, Md. and Bhattacharya, S. S. and Fasel, Claudia and Hahn, Horst
Title: Effect of Gas Flow Rates on the Anatase–Rutile Transformation Temperature of Nanocrystalline TiO2 Synthesised by Chemical Vapour Synthesis
Language: English
Abstract:

Of the three crystallographic allotropes of nanocrystalline titania (rutile, anatase and brookite), anatase exhibits the greatest potential for a variety of applications, especially in the area of catalysis and sensors. However, with rutile being thermodynamically the most stable phase, anatase tends to transform into rutile on heating to temperatures in the range of 500 °C to 700 °C. Efforts made to stabilize the anatase phase at higher temperatures by doping with metal oxides suffer from the problems of having a large amorphous content on synthesis as well as the formation of secondary impurity phases on doping. Recent studies have suggested that the as-synthesised phase composition, crystallite size, initial surface area and processing conditions greatly influence the anatase to rutile transformation temperature. In this study nanocrystalline titania was synthesised in the anatase form by a chemical vapour synthesis (CVS) method using titanium tetra iso-propoxide (TTIP) as a precursor under varying flow rates of oxygen and helium. The anatase to rutile transformation was studied using high temperature X-ray diffraction (HTXRD) and simultaneous thermogravimetric analysis (STA), followed by transmission electron microscopy (TEM). It was demonstrated that the anatase-rutile transformation temperatures were dependent on the oxygen to helium flow rate ratio during CVS and the results are presented and discussed.

Journal or Publication Title: Journal of Nanoscience and Nanotechnology
Volume: 9
Number: 9
Publisher: ASP
Uncontrolled Keywords: NANOCRYSTALLINE TITANIA, ANATASE, RUTILE, TRANSFORMATION TEMPERATURES
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
Date Deposited: 13 Apr 2012 08:48
Official URL: http://dx.doi.org/10.1166/jnn.2009.1110
Identification Number: doi:10.1166/jnn.2009.1110
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