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Low-temperature perovskite-type cadmium titanate thin films derived from a simple particulate sol-gel process

Mohammadi, M. R ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. DOI: 10.1016/j.actamat.2008.10.040
  3. Publisher: 2009
  4. Abstract:
  5. Low-temperature perovskite-type cadmium titanate (CdTiO3) with a nanocrystalline and mesoporous structure was prepared at various Ti:Cd molar ratios by a straightforward particulate sol-gel route. The prepared sols had a narrow particle size distribution, in the range 23-26 nm. X-ray diffraction and Fourier transform infrared spectroscopy revealed that the powders contained a mixture of ilmenite-CdTiO3, perovskite-CdTiO3, anatase and rutile phases, depending on the annealing temperature and the Ti:Cd molar ratio. Perovskite-CdTiO3 was the major type obtained from cadmium-prominent powders at low temperature, whereas ilmenite-CdTiO3 was the major type obtained from titanium-prominent powders at high temperature. It was observed that the anatase-to-rutile phase transformation accelerated with decreasing Ti:Cd molar ratio. Furthermore, the ilmenite-to-perovskite phase transformation accelerated with a decrease in both the Ti:Cd molar ratio and the annealing temperature. The crystallite sizes of the ilmenite- and perovskite-CdTiO3 phases reduced with increasing the Ti:Cd molar ratio. Field emission scanning electron microscopic analysis revealed that the average grain size of the thin films decreased with an increase in the Ti:Cd molar ratio. Moreover, atomic force microscope images showed that CdTiO3 thin films had a columnar-like morphology. Based on Brunauer-Emmett-Taylor analysis, cadmium titanate powder containing Ti:Cd = 75:25 showed the greatest surface area and roughness and the smallest pore size among all the powders annealed at 500 °C. This is one of the smallest crystallite sizes and largest surface areas reported in the literature, and can be used in many applications in areas from optical electronics to gas sensors. © 2008 Acta Materialia Inc
  6. Keywords:
  7. Cadmium titanate ; Low temperature ; Nanocrystalline ; Perovskite ; Sol-gel ; Annealing ; Colloids ; Crystallite size ; Crystallites ; Emission spectroscopy ; Field emission ; Film preparation ; Fourier transform infrared spectroscopy ; Fourier transforms ; Gelation ; Gels ; Ilmenite ; Infrared spectroscopy ; Nanocrystalline alloys ; Nanocrystalline materials ; Nanocrystalline powders ; Optical sensors ; Oxide minerals ; Perovskite ; Powders ; Scanning electron microscopy ; Sol-gel process ; Sol-gels ; Sols ; Spectroscopic analysis ; Thin films ; Titanium ; Titanium dioxide ; Titanium oxides ; Annealing temperatures ; Atomic force microscope images ; Average grain sizes ; Cadmium titanate ; Field emission scanning ; Fourier Transform Infrared ; Gas sensors ; High temperatures ; Low temperature ; Mesoporous structures ; Molar ratios ; Nanocrystalline ; Optical electronics ; Particle size distributions ; Perovskite phase ; Rutile phase ; Rutile phasis ; Sol-gel ; Sol-gel routes ; Surface areas ; Taylor analysis ; X- ray diffractions ; Cadmium
  8. Source: Acta Materialia ; Volume 57, Issue 4 , 2009 , Pages 1049-1059 ; 13596454 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S1359645408007866