研究目的
Investigating the application of V2O5 thin films as NO2 gas sensors and the effect of metal-insulator transition (MIT) on sensor performance.
研究成果
The V2O5 thin films were sensitive to NO2 at relatively low operating temperatures, with a considerable increase of the sensor sensitivity observed above 545 K, related to postulated metal-insulator transition. The study will be continued regarding selectivity.
研究不足
The study focuses on the sensitivity of V2O5 thin films to NO2 at relatively low operating temperatures, with selectivity (especially in respect to water vapor) to be further investigated.
1：Experimental Design and Method Selection
Vanadium pentoxide thin films were deposited onto insulating support by means of rf reactive sputtering from a metallic vanadium target. Argon-oxygen gas mixtures of different compositions controlled by the flow rates were used for sputtering.
2：Sample Selection and Data Sources
The films were deposited onto insulating support (either fused silica or alumina) for sample characterization or conductometric sensor substrate type CC1.W (BVT Technologies, Czech Rep.), for electrical measurements.
3：List of Experimental Equipment and Materials
NOVA NANOSEM 200 (FEI Europe Company) microscope for SEM studies, X-ray diffraction at glancing incidence (GIXD) for phase composition studies, Keithley 6517 electrometer for electrical resistance measurements.
4：Experimental Procedures and Operational Workflow
The responses S of films to the target gas (NO2), defined as changes in electrical resistance (S = RNO2/Rair), were measured by custom-made setup at different NO2 concentrations (0–20 ppm). The sample was placed in a gas chamber on a workholder, where the temperature and gas atmosphere (gas composition and humidity) were stabilized.
5：Data Analysis Methods
The sensor response S was analyzed versus temperature and NO2 concentration. The abrupt increase in the sensor response was observed at 545–547 K, explained by the occurrence of the metal-insulator transition, MIT.
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