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New approaches in lowering the gas-phase synthesis temperature of TiO2 nanoparticles by H2O-assisted atmospheric pressure CVS process

Rahiminezhad Soltani, M ; Sharif University of Technology | 2019

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  1. Type of Document: Article
  2. DOI: 10.1016/j.jmrt.2018.12.027
  3. Publisher: Elsevier Editora Ltda , 2019
  4. Abstract:
  5. H2O-assisted atmospheric pressure chemical vapor synthesis is a modern economical process for the gas-phase synthesis of TiO2 nanoparticles. In the present work, the influence of synthesis temperatures (100-800 °C) on the phase structure, nanoparticle size, morphology, and agglomeration is investigated by transmission electron microscopy, selected area electron diffraction, X-ray diffraction, thermogravimetry, and differential thermal analysis. Down to 400 °C, crystalline TiO2 nanoparticles are synthesized and at 200 °C amorphous nanoparticles are formed. Therefore, a decrease in minimum synthesis temperature by more than 500 °C is achieved. In addition, the paper investigates the hypothesis that the high heat capacity of the H2O particles is responsible for the achieved decrease in synthesis temperature and for the dramatic decrease in size, coalescence, coagulation, and agglomeration of the nanoparticles. It is shown that the nanoparticles size is considerably higher for nanoparticles produced with gas-phase H2O particles in comparison to those produced with liquid-phase H2O particles, (average size 13 and 41 nm, respectively), because of the lower heat capacity of gas-phase H2O particles, thus confirming the hypothesis. © 2019 The Authors
  6. Keywords:
  7. CVS ; Gas phase reaction ; Low-temperature synthesis ; Nanopowders ; Atmospheric chemistry ; Atmospheric pressure ; Atmospheric temperature ; High resolution transmission electron microscopy ; Low temperature effects ; Nanoparticles ; Phase interfaces ; Phase structure ; Specific heat ; Synthesis (chemical) ; Thermogravimetric analysis ; Titanium dioxide ; Chemical vapor synthesis ; Differential thermals ; Gas-phase reactions ; Gas-phase synthesis ; Low temperatures ; Nano powders ; Nanoparticles sizes ; Synthesis temperatures ; TiO2 nanoparticles
  8. Source: Journal of Materials Research and Technology ; Volume 8, Issue 3 , 2019 , Pages 3024-3035 ; 22387854 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S2238785417302387