Physique

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Browsing Physique by Subject "spray pyrolysis"

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    Elaboration, by spray pyrolysis, and characterization of ZnMO (M=Mn, Co, Fe) thin films
    (Université 20 août 1955-Skikda, 2025-11-12) Romeissa , NETTOUR; Abdenour , KABIR
    Transition metals TM (Co, Fe, and Mn) doping induced changes in structural and optical properties of spray deposited ZnO thin films has been studied using X-ray diffraction (XRD), Raman spectroscopy, ATR-FTIR spectroscopy, UV-visible spectroscopy, and photoluminescence spectroscopy (PL) respectively. As a function of TM molar ratio x, XRD patterns revealed a change of crystalline parameters depending on TM nature. For Co doping, Co3O4 and Zn(OH)2 secondary phases appeared for x=0.10. for Mn doping, secondary phases such as MnO2 and ZnMnO3 appeared for x=0.06 while for Fe doping, no secondary phase was observed. These results were evidenced by Raman spectroscopy and ATR-FTIR spectroscopy. For the three doping elements, the band gap energy of ZnO varied, as a function of TM molar ratio x depending on TM nature. For Co doping, the band gap energy of ZnCoO decreased from 3.45 eV, for x=0.00, to reach a minimal value of 2.67 eV for x=0.08. For Fe doping, the band gap energy of ZnFeO decreased to reach a minimum of 3.21 eV for x=0.04. Beyond this molar ratio, the band gap energy stabilized around 3.27 eV. However, for Mn doping, the band gap energy of ZnMnO increased to reach a maximum of 3.55 eV for x=0.06. The photoluminescence spectrum of ZnO presented two peaks: an ultraviolet emission peak around 375 nm and a near infrared emission peak around 754 nm. Photoluminescence properties of samples depend on the TM nature and the TM molar ratio x. For Fe doping, the intensity of these two peaks decreased as a function of Fe molar ratio. No other emission peaks were observed. For Co doping, the intensity of these two peaks decreased as a function of Co molar ratio, to completely disappear for x=0.10 leaving their place to a red emission peak attributed to Co based impurities. For Mn doping, the intensity of UV and NIR emission peaks decreased rapidly for x=0.02. for x=0.04 and x=0.06, these two emission peaks disappeared leaving their places for a violet, a blue, and a blue-green emissions attributed respectively to Mn ions, Zni et VZn.
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    Study of the structural, optical, and electrical properties of copper oxide thin films undoped and doped
    (University of 20 aout 1955-Skikda, 2024-05-09) ZEROUALI, Madiha; Daira, Radouane
    In this study, copper oxide thin films undoped and doped were elaborated by two methods: pneumatic spray pyrolysis and sol-gel spin coating on a glass substrate, and used in two applications: self-cleaning and photocatalytic, respectively. All the samples are characterized by X-ray diffraction, FT-IR spectroscopy, scanning electron microscope, energy-dispersive Xray, UV-visible spectrophotometry, and four-point method. Undoped CuO layers were made by spray pyrolysis for different spray times. The XRD analysis of these layers showed that the films have a monoclinic structure (tenorite) and a preferential growth in the (111) direction. According to Scherer's formula the crystallite size is nanometric between 14 – 23nm. The water contact angle values in all samples are greater than 90° and range from 96.4° to 103.2°, as we can see from these results that all the samples are hydrophobic films and excellent in a selfcleaning application. Thin films of copper oxide undoped and doped with aluminum and silver (5%, 15%, 25 %, and 50%) were deposited by the sol-gel spin coating method on a glass substrate. According to XRD diffraction and by Williamson-Hall plot method, the crystallite size varies between 21– 46 nm and 21– 33 nm and increases with the increase in Al and Ag doping, respectively. The electrical conductivity values increase with the presence of doping. Aluminum doping has good structural and electrical properties when compared to elemental silver. The Photocatalysis results showed that doping of copper oxide by (Al) improves the photocatalytic efficiency, and the best degradation of a dye (orange II) under UV irradiation after 5 hours reaches 61% for the use for thin layers of CuO doped with 50% Al.