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Effect of Dopants in Vapor Phase Synthesis of Titania Powders

Published online by Cambridge University Press:  25 February 2011

M. Kamal Akhtar
Affiliation:
Department of Chemical Engineering, Center for Aerosol Processes, University of Cincinnati, Cincinnati, OH 45221.
S. E. Pratsinis
Affiliation:
Department of Chemical Engineering, Center for Aerosol Processes, University of Cincinnati, Cincinnati, OH 45221.
S. V. R. Mastrangelo
Affiliation:
DuPont Chemicals, Edge Moor, DE 19809.
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Abstract

Gas phase synthesis of titania from titanium tetrachloride (Ticl4) oxidation in the presence of dopants (SiCl4 and POCl3) was systematically investigated in an aerosol reactor as a function of temperature (1300–1700 K) and dopant concentration (0–15 mole % of TiCl4). The particle morphology was dramatically altered in the presence of dopants from polyhedral to spherical. Energy dispersive analysis indicated that the powders were homogeneous and that the dopants were not segregated at the surface or at the grain boundaries. Lattice parameter measurements from X-ray diffraction indicated that the dopant oxide was present in solid solution in titania. While titania synthesized in the absence of dopants was ∼80% anatase, the introduction of Si4+ and P5+ resulted in greater than 98 % anatase. The effects of foreign ions on titania phase composition, aggregate size and gas phase coalescence are explained by the creation of oxygen vacancies and reduction/enhancement of the titania sintering rates.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

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References

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