Preparation of core-shell Ti-Nb oxide nanocrystals
- 161 Downloads
Nanosized powders of Ti-Nb oxide core-shell nanocrystals with atomic ratios of Nb/Ti = 0.11, 0.25, and 0.38 have been prepared by two preparation routes. The first route was co-precipitation, followed by␣annealing, using NbCl5 as a source of Nb. The second route was coating of pure TiO2 nanocrystals by Nb-isopropoxide in liquid medium, followed by impregnation of the Nb into the nanoparticles by annealing. Both methods yielded anatase nanocrystals with a Nb-rich shell and a core, which had much lower Nb loadings. The anatase structure solid solution (with Nb incorporated) was stable under annealing up to 760°C. The particle size remained within the nanometric scale (<50 nm) under heat-treatment up to 760°C. It has been shown that the fabricated powders can be redispersed in aqueous media by simple ultrasound treatment, resulting in nanosized dispersions. Using a variety of analytical techniques, including depth profiling of single nanocrystallites by AES combined with sputtering by Ar ions, the mechanism of the core-shell structure creation was studied. It is proposed that the formation of the core-shell structure is governed by solubility limitations in the co-precipitation route and by solubility and diffusion limitations in the coating-incorporation route.
Keywordstitania anatase niobium solid solutions core-shell nanocrystallite nanosized dispersion coating wet synthesis
Unable to display preview. Download preview PDF.
- Hirano M., Matsushima K. (2006) Effect of niobium on the structure and photoactivity of anatase (TiO2) nanoparticles. J. Nanosci. Nanotechnol. 6(3):762–770Google Scholar
- Simakov S.A., Tsur Y. (2006) Surface stabilization of nano-sized titanium oxide: Improving the colloidal stability and the sintering morphology. J. Nanopart. Res., DOI 10.1007/s11051-006-9099-0
- Whang C.M., Kim J.G., Hwang H.J. (2005) Photocatalytic properties of the transition metal doped TiO2 powder prepared by Sol-Gel process. Key Eng. Mater. 1:280–283Google Scholar
- Young R.A. (1993) The Rietveld Method. Oxford University PressGoogle Scholar
- Zaban A., S.G. Chen, S. Chappel, B.A. Gregg, 2000. Bilayer nanoporous electrodes for dye sensitized solar cells. Chem. Commun. 2231–2232Google Scholar