Development of semiconductor fluorocarbon gas sensor

✍ Scribed by T. Nomura; T. Amamoto; Y. Matsuura; Y. Kajiyama

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 287 KB
• Volume: 13
• Category: Article
• ISSN: 0925-4005
• DOI: 10.1016/0925-4005(93)85434-c

✦ Synopsis

To improve the sensitivity to fluorocarbon, surface-modification effects on fluorocarbon detection of a gas sensor based on metal oxides such as SnO,, ZnO, In,O,, Fe,O, and WO, have been examined. It is proved that SnOz is the most suitable material for fluorocarbon detection. 39 kinds of elements have be-en investigated as the additives to SnOl, which significantly affect its sensing characteristics. It is cordirmed that sulfur is the most effective modifier to improve the sensitivity. The surface modification of SnOz with 1.0 mol% of sulfur induced the enhancement of sensitivity by a factor of 6.5 for CCI,FCCIF, (R-113). Furthermore, the selectivity is also improved by this modification. The sensor doped with 1.0 mol% of sulfur can even detect gas leakage as low as 5 ppm of CH,FC!F, (R-134a) and shows no impairment in long-term stability. IR results have convinced us that the doped sulfur exists in bidentate coordinated form as the sulfate ion (SO,'-) on the Sn atom. The sulfur acts as an active site to decompose fluorocarbon (the severance of C-Cl and C-F bonds in fluorocarbon molecules).