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Synthesis of nanostructured and nanoporous TiO2-AgO mixed oxide derived from a particulate sol-gel route: Physical and sensing characteristics

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

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  1. Type of Document: Article
  2. DOI: 10.1007/s11661-011-0644-9
  3. Publisher: 2011
  4. Abstract:
  5. Nanocrystalline TiO2-AgO thin films and powders were prepared by an aqueous particulate sol-gel route at the low temperature of 573 K (300 °C). Titanium tetraisopropoxide and silver nitrate were used as precursors, 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 phase composition of the mixed oxide depends upon the annealing temperature, being a mixture of TiO2 and AgO in the range 573 K to 773 K (300 °C to 500 °C) and a mixture of TiO2, AgO, Ag2O at 973 K (700 °C). Furthermore, one of the smallest crystallite sizes was obtained for TiO 2-AgO mixed oxide, being 4 nm at 773 K (500 °C). Field emission-scanning electron microscopic (FE-SEM) and atomic force microscopic (AFM) images revealed that the deposited thin films had nanostructured and nanoporous morphology with columnar topography. Thin films produced under optimized conditions showed excellent microstructural properties for gas sensing applications. They exhibited a remarkable response toward low concentrations of CO gas (i.e., 25 ppm) at low operating temperature of 473 K (200 °C), resulting in an increase of the thermal stability of sensing films as well as a decrease in their power consumption. Furthermore, TiO2-AgO sensors follow the power law for the detection of CO gas
  6. Keywords:
  7. AFM ; Annealing temperatures ; Atomic force ; FTIR ; Gas sensing applications ; Hydroxypropyl cellulose ; Low concentrations ; Low operating temperature ; Low temperatures ; Microstructural properties ; Mixed oxide ; Nano-structured ; Nanocrystalline TiO ; Nanoporous morphologies ; Nanoporous TiO ; Optimized conditions ; Power law ; Sensing characteristics ; Sensing films ; Silver nitrates ; TiO ; Titanium tetraisopropoxide ; Fourier transform infrared spectroscopy ; Gas sensing electrodes ; Gels ; Sol-gel process ; Sol-gels ; Sols ; Thermodynamic stability ; Thin films ; Titanium ; Titanium dioxide ; Topography ; X ray diffraction ; Silver oxides
  8. Source: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 42, Issue 8 , August , 2011 , Pages 2481-2492 ; 10735623 (ISSN)
  9. URL: http://link.springer.com/article/10.1007%2Fs11661-011-0644-9