Abstract
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. X-ray diffraction at glancing incidence (GIXD) and Scanning Electronic Microscopy (SEM) were used for structural and phase characterization. Thickness of the films was determined by the profilometry. It has been confirmed by GIXD that the deposited films are composed of V2O5 phase. The gas sensing properties of V2O5 thin films were investigated at temperatures from range 410–617 K upon NO2 gas of 4–20 ppm. The investigated material exhibited good response and reversibility towards nitrogen dioxide. The effect of metal-insulator transition (MIT) on sensor performance has been observed and discussed for the first time. It was found that a considerable increase of the sensor sensitivity occured above 545 K, which is related to postulated metal-insulator transition.
Highlights
Increasing environmental pollution is becoming a vital global concern, in relation to the imperative to reduce emissions of gases causing the greenhouse effect, acid rain, and the depletion of stratospheric ozone
Chemical gas sensors may offer advantages in the form of simple construction, low cost and ability to work in situ
One large group of sensors, applied to environmental monitoring, is based on liquid electrochemistry. These sensors presently suffer from the same four severe disadvantages. These sensors cannot be applied in environments warmer than room temperature
Summary
Increasing environmental pollution is becoming a vital global concern, in relation to the imperative to reduce emissions of gases causing the greenhouse effect, acid rain, and the depletion of stratospheric ozone. Sophisticated and expensive equipment, such as gas analyzers based on IR and UV spectrophotometry, pulse fluorescence, flame photometry and gas chromatography, to determine air quality were applied. This equipment enables very precise gas phase analysis, it has four substantial disadvantages such as high cost, large dimensions (limited portability), slow analysis time and non-continuous monitoring of the gas composition. One large group of sensors, applied to environmental monitoring, is based on liquid (or wet) electrochemistry These sensors presently suffer from the same four severe disadvantages. These sensors cannot be applied in environments warmer than room temperature
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