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Synthesis and characterisation of nanosized TiO2-ZrO2 binary system prepared by an aqueous sol-gel process: Physical and sensing properties

Mohammadi, M. R ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.1016/j.snb.2011.01.009
  3. Publisher: 2011
  4. Abstract:
  5. Nanostructured TiO2-ZrO2 thin films and powders were prepared by a straightforward aqueous particulate sol-gel route. Titanium (IV) isopropoxide and zirconium (IV) acetate hydrate 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 (FTIR) spectroscopy revealed that the powder were crystallised at the low temperature of 500 °C, containing anatase-TiO 2 and tetragonal-ZrO2 phases. Furthermore, it was found that ZrO2 retarded the anatase-to-rutile transformation up to 900 °C. The activation energies for crystallite growth of TiO2 and ZrO2 components in the binary system were calculated 10.16 and 3.12 kJ/mol, respectively. Transmission electron microscope (TEM) image showed that one of the smallest crystallite sizes was obtained for TiO2-ZrO 2 binary mixed oxide, being 5 nm at 500 °C. Field emission scanning electron microscope (FESEM) analysis revealed that the deposited thin films had nanostructured morphology with the average grain size of 20 nm at 500 °C and 36 nm at 900 °C. Thin films produced under optimised conditions showed excellent microstructural properties for gas sensing applications. They exhibited a remarkable response towards low concentrations of CO and NO 2 gases at low operating temperature of 150 °C, resulted in an increase of thermal stability of sensing films as well as a decrease in the power consumption. Furthermore, calibration curves revealed that TiO 2-ZrO2 sensor follows the power law, S = A[gas] B (where S is sensor response, coefficients A and B are constants and [gas] is gas concentration) for the two types of gases, and it has excellent capability for the detection of low gas concentrations
  6. Keywords:
  7. Nanostructure ; Zirconium oxide ; Anatase-to-rutile transformations ; Aqueous sol-gel ; Average grain size ; Binary mixed oxides ; Binary systems ; Calibration curves ; Characterisation ; CO and NO ; Crystallite growth ; Field emission scanning electron microscopes ; Fourier transform infrared ; Gas concentration ; Gas sensing applications ; Hydroxypropyl cellulose ; Iso-propoxide ; Low concentrations ; Low operating temperature ; Low temperatures ; Microstructural properties ; Nanosized TiO ; Nanostructured morphology ; Nanostructured TiO ; Optimised conditions ; Power Consumption ; Power law ; Sensing films ; Sensing property ; Sensor response ; Sol-gel routes ; Thermal stability ; TiO ; Transmission electron microscope ; Activation energy ; Crystallites ; Electron microscopes ; Field emission ; Film preparation ; Fourier transforms ; Gas sensing electrodes ; Gases ; Gels ; Nanostructures ; Oxide minerals ; Scanning electron microscopy ; Sensors ; Sol-gels ; Sols ; Systems (metallurgical) ; Thermodynamic stability ; Thin films ; Titanium ; Titanium dioxide ; X ray diffraction ; Zirconia ; Zirconium ; Zirconium alloys ; Sol-gel process
  8. Source: Sensors and Actuators, B: Chemical ; Volume 155, Issue 2 , July , 2011 , Pages 568-576 ; 09254005 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0925400511000268