<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">H₂S gas sensing characteristics of WO₃ thick-films</span>

Abstract

<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">The WO₃ thick-films fabricated as gas sensor exhibit good sensitivity for H₂S over a wide range of operation temperatures.The sensor characteristics are influenced with the microstructure and the thickness of the WO₃ films. The sensitivity of the sensor decreases with increase in thickness of the films. Re lative variation of the fabricated sensor's resistance at varying temperatures between 240° and 420°C with heater power and with varying concentrations of the H₂S gas under analysis have been derived. The best results for sensing H₂S gas in the concentration range between 0.05 and 25 ppm have been obtained when the film thickness is kept between <span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:hiddenhorzocr;color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">20 -22 μm . <span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">The response of WO₃ films for sensing H₂S gas is not influenced by the presence of several testing reference gases like SO₂ up to 12 ppm, NH₃ up to 10.8 ppm, CO up to 19 ppm and CH₄ up to 187 ppm. However, presence of NO, interferes when present in ambient air. Addition of small amounts of SO₂ (3-10%), however, corrects the result and H₂S can be determined in the presence of NO_x up to 11 ppm.</span></span></span>