8-12 July 2013
Synthesis, characterization and gas sensing applications of Tungsten Trioxide
Presented by Mr. Malcolm GOVENDER on 10 Jul 2013 from 09:40 to 10:00
Type: Oral Presentation
Track: Track A - Division for Condensed Matter Physics and Materials
Tungsten trioxide film was RF-sputtered onto alumina substrates. SEM studies over the sample area (1 cm<sup>2</sup>) showed uniform topology while FIB cross-sectioning showed the thickness to vary between 0.75-1.50 µm and this variation stems from the alumina roughness. The measured film resistance using a two-probe setup was found to be 5 kΩ at room temperature, and decreased to 2 kΩ at 300<sup>o</sup>C which is expected for n-type semiconducting materials. Raman spectroscopy of the films showed Raman shifts at approximately 267 cm<sup>-1</sup>, 700 cm<sup>-1</sup> and 800 cm<sup>-1</sup> which are indicative of tungsten trioxide. The films were used to sense ppm concentrations of NO<sub>2</sub> and NH<sub>3</sub> gas, and it was found that the film gave best response to both gases at 200<sup>o</sup>C. The film showed higher sensitivity to NO<sub>2</sub> than to NH<sub>3</sub>, presumably due to the adsorption mechanism between sensing an oxidizing gas and reducing gas.
Bonex W. Mwakikunga, BMwakikunga@csir.co.za CSIR-NCNSM