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Low temperature nanocrystalline TiO 2-Fe 2O 3 mixed oxide by a particulate sol-gel route: Physical and sensing characteristics

Mohammadi, M. R ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1016/j.physe.2012.09.002
  3. Publisher: Elsevier , 2012
  4. Abstract:
  5. Nanocrystalline TiO 2-Fe 2O 3 thin films and powders were prepared by a straightforward aqueous particulate sol-gel route at the low temperature of 300 °C. Titanium(IV) isopropoxide and iron(III) chloride were used as precursors, and hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the powder crystallised at the low temperature of 300 °C, containing anatase-TiO 2 and hematite-Fe 2O 3 phases. Furthermore, it was found that Fe 2O 3 retarded the anatase-to-rutile transformation up to 500 °C. The activation energies for crystallite growth of TiO 2 and Fe 2O 3 components in the binary system were calculated 10.62 and 0.67 kJ/mol, respectively. Moreover, one of the smallest crystallite sizes was obtained for TiO 2-Fe 2O 3 binary mixed oxide, being 6 nm at 300 °C. Field emission scanning electron microscope (FE-SEM) analysis revealed that the deposited thin films had nanostructured morphology. Thin films produced under optimized conditions showed excellent microstructural properties for gas sensing applications. They exhibited a remarkable response towards low concentrations of CO gas (i.e., 25 ppm) at low operating temperature of 150 °C, resulting in increased thermal stability of sensing films as well as a decrease in their power consumption. Furthermore, TiO 2-Fe 2O 3 sensors follow the power law for the detection of CO gas
  6. Keywords:
  7. Anatase-to-rutile transformations ; Binary mixed oxides ; Binary systems ; Crystallite growth ; Field emission scanning electron microscopes ; Gas sensing applications ; Hydroxypropyl cellulose ; Iron chlorides ; Iso-propoxide ; Low concentrations ; Low operating temperature ; Low temperatures ; Microstructural properties ; Mixed oxide ; Nanocrystalline TiO ; Nanostructured morphology ; Optimized conditions ; Sensing characteristics ; Sensing films ; Sol-gel routes ; TiO ; Activation energy ; Chlorine compounds ; Fourier transform infrared spectroscopy ; Gas sensing electrodes ; Iron compounds ; Nanocrystalline powders ; Oxide minerals ; Sol-gel process ; Temperature ; Thin films ; Titanium ; X ray diffraction ; Titanium dioxide
  8. Source: Physica E: Low-Dimensional Systems and Nanostructures ; Volume 46 , September , 2012 , Pages 43-51 ; 13869477 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S1386947712003323