In this work, Nitrogen dioxide gas sensorwas manufactured from SnO 2 and (SnO 2) 1-x (In 2 O 3) x at different atomic ratios (x=0.05, 0.1 and 0.15) using pulsed laser deposition technique. The effect of the preparation ratio on structural properties, surface topography, optical and electrical characteristics and gas sensor efficiency were studied. The x-ray diffraction measurements showed polycrystalline structures for all samples and their crystallite size decreases with increasing the doping ratio. The AFM measurement illustrates spherical SnO 2 shapes converted to filament-like shapes at x=0.1, and that the average particle diameter decreased, while the RMS roughness increased with increasing ratio. The best samples in terms of gas sensitivity were produced at the 0.1 ratio due to the associated with low particle sizes and high charge carrier concentration. The highest gas sensitivity appeared at 200 °C operating temperature, and it is increased with gas concentration as a second-order equation and be nearly stable at 400 ppm NO 2 gas. The best sample appeared at 10% In 2 O 3 :SnO 2 atomic ratio.
Tin dioxide (SnO 2) and tin dioxide: polyethylene glycol (SnO 2 : PEG) nano-composite thin films, at 10 and 20 wt % PEG, were fabricated by spin coating techniques from a mixed solution of ethanol and water. The structural, morphological, and optical properties of the prepared samples were examined to study the effect of PEG addition on SnO 2 thin film properties. X-ray diffraction shows a polycrystalline structure for all samples, where the crystalline size reduced from 8.3 nm (for the pure sample) to 7.2 nm (for the 20% PEG sample). The addition of PEG with the precursors significantly affected the growth behaviour of SnO 2 nanoparticles, where the nanoparticle diameter reduced and the connection between them was enhanced forming a continuous structure with pores that enhance gas sensitivity. The hydrogen (H 2) gas sensitivity, for the prepared SnO 2 and SnO 2 :PEG samples, increased by increasing the PEG content from 0 to 20% by about four times. The optimum sensitivity was at the working temperature of 100 °C. The gas sensitivity was exponentially dependent on H 2 gas concentration across a concentration range of 100 to 4000 ppm.
We prepared polythiophene (PTH) with single wall carbon nanotube (SWCNT) nanocomposite thin films for Nitrogen dioxide (NO2) gas sensing applications. Thin films were synthesized via electrochemical polymerization method onto (Indium tin oxide) ITO coated glass substrate of thiophene monomer with magnesium perchlorate and different concentration from SWCNT (0.012 and 0.016) % in the presence130mL of Acetonitrile used. X-ray diffraction (XRD), Field Emission Scanning Electron microscopy (FE-SEM), Atomic Force Microscope (AFM) and Fourier Transform Infrared Spectroscopy (FT-IR) were used to characterized these nanocomposite thin films. The response of these nanocomposite for NO2 gas was evaluated via monitoring the change time in presence 25% NO2 of with electrical resistance at (40, 80,120,160 and 200)°C. We can observe that the PTh/SWCNT films show a higher sensitivity as compare to pure PTH.
In this work, a reactive DC magnetron sputtering technique was used to prepare TiO2 thin films. The variation in argon and oxygen gases mixing ratios (4:1, 2:1, 1:1, 1:2, 1:4) was used to achieve optimal properties for gas sensing. In addition, an analysis of the optical XRD properties of TiO2 thin films is presented. High-quality and uniform nanocrystalline films were obtained at a working gas pressure of 0.25 mbar and 1:4 (Ar/O2) gas mixture. The optical properties showed a transparent thin film with uniform adherence to the substrate. The average transmission of the TiO2 films deposited on the glass substrates was higher than 95% over the range of 400 to 800 nm. The optical band gap varied from 3.84 eV to 3.93 eV as a function of oxygen/argon ratios. The XRD pattern showed that the films have an amorphous structure, which is shifted to polycrystalline with increasing oxygen to argon ratio. The sensitivity, response time, and recovery time were measured for TiO2 thin films using NO2 oxidizing gas.
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