Phase transformation and precipitation behavior of niobium component out of niobium-doped anatase-type TiO2 nanoparticles synthesized via hydrothermal crystallization

The precipitation behavior of niobium component out of niobium-doped anatase-type TiO 2 and structural change in the course of heating were investigated. The samples were directly formed under hydrothermal conditions at 240 °C for 5 h in the presence of aqueous ammonia via crystallization from co-pr...

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Bibliographic Details
Published in:Journal of materials science 2009-11, Vol.44 (22), p.6135-6143
Main Authors: Hirano, Masanori, Ichihashi, Yoshiko
Format: Article
Language:English
Subjects:
Ammonia
Anatase
Characterization and Evaluation of Materials
Chemistry and Materials Science
Classical Mechanics
Crystallization
Crystallography and Scattering Methods
Electron paramagnetic resonance
Heating
Lattice parameters
Materials Science
Nanoparticles
Niobium
Niobium oxides
Phase transformations
Phase transitions
Polymer Sciences
Precipitates
Precipitation
Rutile
Solid Mechanics
Solid solutions
Titanium
Titanium dioxide
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Summary:The precipitation behavior of niobium component out of niobium-doped anatase-type TiO 2 and structural change in the course of heating were investigated. The samples were directly formed under hydrothermal conditions at 240 °C for 5 h in the presence of aqueous ammonia via crystallization from co-precipitates that were obtained from precursor solutions of TiOSO 4 and NbCl 5 . The as-prepared niobium-doped anatase-type titania nanoparticles showed bluish color and absorption in the visible region, which was confirmed to be due to the presence of Ti(III) in the solid solutions using electron paramagnetic resonance measurement. The niobium-doped anatase-type titania existed stably without an appearance of any other phases after heating up to 500 °C for 1 h. In the course of heating at 500–800 °C, continual and clear decrease in the lattice parameters a 0 and c 0 of the anatase was observed, which was followed by the precipitation of Nb 2 O 5 and TiNb 2 O 7 out of the niobium-doped anatase, but the anatase phase was maintained without anatase-to-rutile phase transformation up to 850–1,000 °C. The anatase-to-rutile phase transformation was gradually retarded when the niobium content increased.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-009-3848-2