Preparation of hexagonal WO3 from hexagonal ammonium tungsten bronze for sensing NH3

Imre Miklós Szilágyi, Lisheng Wang, Pelagia Irene Gouma, Csaba Balázsi, János Madarász, György Pokol

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Abstract

Hexagonal tungsten oxide (h-WO3) was prepared by annealing hexagonal ammonium tungsten bronze, (NH4)0.07(NH3)0.04(H 2O)0.09WO2.95. The structure, composition and morphology of h-WO3 were studied by XRD, XPS, Raman, 1H MAS (magic angle spinning) NMR, scanning electron microscopy (SEM), and BET-N2 specific surface area measurement, while its thermal stability was investigated by in situ XRD. The h-WO3 sample was built up by 50-100 nm particles, had an average specific surface area of 8.3 m2/g and was thermally stable up to 450 °C. Gas sensing tests showed that h-WO3 was sensitive to various levels (10-50 ppm) of NH3, with the shortest response and recovery times (1.3 and 3.8 min, respectively) to 50 ppm NH3. To this NH3 concentration, the sensor had significantly higher sensitivity than h-WO3 samples prepared by wet chemical methods.

Original languageEnglish
Pages (from-to)505-508
Number of pages4
JournalMaterials Research Bulletin
Volume44
Issue number3
DOIs
Publication statusPublished - Mar 5 2009

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Keywords

  • A. Oxides
  • C. X-ray diffraction
  • D. Electrical properties
  • Electron microscopy
  • Semiconductors

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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