Elaboration of pure and doped ZnO powders with the sol gel method

Latif, Aya (2024) Elaboration of pure and doped ZnO powders with the sol gel method. Doctoral thesis, Université Mohamed Khider (Biskra - Algérie).

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Abstract

Undoped, doped, and co-doped zinc oxide powders with different concentrations of bismuth and gallium were prepared by the chemical sol-gel method using zinc acetate, citric acid, bismuth nitrate, and gallium nitrate as precursors and ethylene glycol as a solvent. The effect of doping on zinc oxide powders' structural, morphological, and optical properties was studied. The powders were characterized using various techniques such as X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, and Fourier Transform Infrared spectroscopy. the results obtained using the X-ray diffraction technique showed that all the prepared powders have a hexagonal crystalline structure with good crystallinity and nanocrystalline size. A blue shift was observed in the UV-visible spectra of gallium-doped zinc oxide powders compared to those doped with bismuth and co-doped with bismuth and gallium. In addition, the results of UV-visible spectroscopy showed that doping zinc oxide powders with gallium led to a significant increase in the band gap energy while doping with bismuth and co-doping with bismuth and gallium showed a decrease in the band gap energy. Infrared spectral analysis showed a specific association with zinc oxide in all samples. The antibacterial activity of the prepared powders was tested against different types of bacteria. The results showed that pure, doped, and co-doped zinc oxide nanoparticles exhibited strong antibacterial activity against a wide range of bacteria, including Gram-negative Escherichia coli, Klebsiella pneumoniae, and Enterobacter aerogenes, as well as Gram-positive Listeria monocytogenes. These findings demonstrate the remarkable effectiveness of zinc oxide in inhibiting bacterial growth. The prepared samples were subjected to voltage-current testing, and the results showed that the type of doping has a significant impact on the electrical behavior of variable zinc oxide resistance. Doping zinc oxide with bismuth led to aremarkable increase in breakdown voltage, indicating an improvement in resistor lifetime. While doping with gallium led to an increase in current leakage. Dual doping of zinc oxide with bismuth and gallium showed promising results, providing a balance between high breakdown voltage and severe current leakage.

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