研究目的
Investigation of the effect of ZnO concentration on the crystallite size, morphology, optical properties, and its response towards NO2 gas, to describe critical factors controlling this response.
研究成果
The 5 wt% of ZnO doped Cr2O3 thin film show the highest sensitivity to NO2 gas, which evaluated 87.5% at an operating temperature of 573 K. The improvement in the sensing performance upon adding ZnO may be attributed to enhanced surface roughness, thereby resulting in faster oxidation rate.
研究不足
The technical and application constraints of the experiments, as well as potential areas for optimization, are not explicitly mentioned in the paper.
1：Experimental Design and Method Selection:
The Cr2O3 powder was mixed with different concentrations of high purity (
2：99%) ZnO (0, 3, 5, 7 and 9 wt%), and the mixture was pressed under a pressure of 6–8 Ton to form a target with 2 cm diameter and 5 cm thickness. The thin films of Cr2O
ZnO were deposited on glass substrates using second harmonic generation pulsed Nd–YAG laser operated at a wavelength of 1064 nm. The laser beam enters a vacuum chamber with an oxygen pressure range of
3：01–5 mbar and is focused on the target surface at 45° angle of incidence. The space between the target and the substrate was about 5 cm, and pulsed laser deposition energy is 600 mJ per pulse. The glass substrates are cleaned using ethanol, followed by sequential rinsing with distilled water using an ultrasonic bath. Sample Selection and Data Sources:
The crystalline structures of the as-synthesized nanoparticles are characterized through X-ray diffractometer model D2 PHASER BRUKER operated at tube voltage 40 kV, and tube current 30 mA, under Cu-Kα radiation (λ = 1.54056 ?). The X-ray diffraction pattern was recorded for 2θ scan angle range from 20° to 80°, with a step size of 0.02°. The surfaces morphology for as-synthesized thin films were examined by atomic force microscope (AFM) scanning probe microscope (SPM), Model AA3000. UV–visible spectrophotometer (Shimadzu, UV-1800) was used to measure the optical absorbance spectrum of the as-prepared thin-films in the wavelength range 300–1100 nm at ambient temperature. A standard optical interferometer technique was used to measure the thickness of the prepared thin films and found to be in the range between (100–110 nm). Gas-sensing studies were carried out by measuring the resistance of thin films in the presence of NO2 gas (Rg) and air (Ra). The NO2 gas was produced when concentrated nitric acid (HNO3) is dropped on a copper pieces to react in a glass container. The produced NO2 gas was dried by filters with a flow rate of 2.5 Nm2/min. The NO2 gas sensitivity, response and recovery times of the thin films were studied and discussed.
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