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Abstract


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IJCPS JOURNAL-Vol 5 Issue 3, May-Jun 2016

Pages: 01-13

Gas Sensing Properties of WO3 Thick Film Resistors Prepared by Screen Printing Technique

Author: ARUN S GARDE

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Abstract

WO3-based thick film resistors were fabricated using screen printing technology. The sensing behavior of WO3 thick film resistors deposited on alumina substrates has been investigated for NH3, H2S, & LPG gas. The films were sintered at optimized temperature of 500OC for 30 minutes. The material characterization was performed by XRD, SEM, and EDAX for elemental analysis. The UV-visible spectra show WO3 exhibits a shoulder at 230 nm along with an ill-defined band at 251.6 nm. The optical band gap energy of 3.9 eV was obtained on a room temperature. The variation of D.C electrical resistance of WO3 film samples was measured in air as well as in NH3, H2S, & LPG gas atmosphere as a function of temperature. The WO3 film samples show negative temperature coefficient of résistance. The WO3 film samples showed the highest sensitivity up to 400 ppm for NH3 (2.94) at 300OC, for H2S (1.15) at 4000C and for LPG (1.14) at 330OC. Selectivity of H2S and LPG gas in comparison with NH3 was relatively poor. The effect of microstructure on sensitivity, response and recovery time of the sensor in the presence of NH3, H2S, & LPG gases were studied and discussed

Keywords: WO3, Thick film, Material behavior, Optical behavior, Gas Sensitivity .