Publications Internationales

Permanent URI for this collectionhttps://dspace.univ-boumerdes.dz/handle/123456789/13

Browse

Subject: search.filters.subject.ZnO

Search Results

Now showing 1 - 10 of 13
  • No Thumbnail Available
    Item
    Phase Transition and Atomic Distances Behavior of ZnO Rocksalt Structure under Extended Pressure: a Parallel and Equilibrium MD Computation Yahia Chergui
    (Preprints, 2023) Chergui, Yahia; Ouatizerga, Abd elaziz; Salah, Essma Redouane
    Zinc oxide (ZnO) as a semiconductor in its crystalline or amorphous form is still a promised material, especially under isobaric and isothermal ensembles. In this work, Parallel and Equilibrium Molecular Dynamics and DL_POLY_4 software are employed to predict the relationship between the behavior of ZnO chemical bonds and the phase transition literatures, using correlation function g(r) of Zn-Zn, Zn-O, and O-O pairs. Our system is composed of 5832 atoms of ZnO rocksalt structure (2916 atoms of Zn2+ and 2916 atoms of O2-), under the temperature of 300 (K) and the range of pressure 0-400 (GPa). The lengths of ZnO bonds, the standard error, standard deviation, the maximum of g(r), and the percentage of the variation of the bonds are analyzed. The interatomic interactions are modeled by the potential of Buckingham for short-range and Coulomb for long-range interactions. The calculations were run on the RAVEN Supercomputer of Cardiff University (UK). Our data are mostly in the vicinity of available information of bonds lengths; the rest can be deduced from the pressure of phase transition to use it as a new approach of phase transition confirmation. However, the rest of our results are still a prediction because of no results under extended pressure used in this work. These data have huge importance, as it is required to be used in many industrial sectors, geophysics, Medicine, and Pharmacy, especially in nanoscale and materials design.
  • No Thumbnail Available
    Item
    Characterization and application of the hetero-system LaCoO3/ZnO for degradation of Orange II under solar light
    (Springer, 2023) Ouatizerga, A.; Rekhila, G.; Mirad, S.; Trari, M.
    LaCoO3 elaborated by nitrate route was characterized physically and electrochemically to be applied in the Orange II (OII) oxidation upon solar light. The X-ray difraction (XRD), SEM analysis and electrical conductivity were undertaken. The difractogram showed that the single phase is completed at 850 °C and the oxide crystallizes in a distorted perovskite structure. The peak at 643 cm−1 in the attenuated total refection (ATR) spectrum confrmed the purity of the phase. The forbidden band (1.35 eV), determined from the difuse refectance, is assigned to Co3+: d-d transition in a low spin confguration (3d6 , E5/2) in conformity with the black color of the oxide. The feld-dependent magnetization was measured at 300 K in the range±25 kOe, and the perovskite exhibits a low magnetism with a saturation magnetization (0.28 emu/g) confrming the low spin state Co3+. The thermal variation of the conductivity is characteristic of non-degenerate behavior and a hole mobility of 10−2 cm2 V−1 s −1 and an activation energy of 0.11 eV. The latter is diferent from that obtained from the thermo-power, a signature of a conduction mechanism by small polaron hopping. LaCoO3 is chemically stable above pH 5; an exchange current density of 40 μA cm−2, a polarization resistance of 1.92 kΩ cm2 and a corrosion potential of 0.99 VSCE were obtained at pH~ 7 (Na2SO4, 0.1 M). Curiously and unlike the perovskites, the variation of the inverse of the square of the capacitance as a function of potential (C−2−E) indicates p type behavior with a fat band potential of 0.30 VSCE and holes density of 1.97× 1017 cm−3. The conduction band (−0.94 VSCE), made up of Co3+: 3d orbital, enables the formation of the radical O2 •−, and as application, the oxide was successfully experimented for the oxidation of OII upon solar irradiation. The hetero-junction p-LaCoO3/n-ZnO enhances considerably the photo-activity, due to the facile transfer of electrons with an abatement of 86% at neutral pH. The oxidation follows a frst-order kinetic with a half photocatalytic life of 23 min
  • No Thumbnail Available
    Item
    Dependence of structural and optical properties of ZnO thin films grown by Sol–Gel Spin-Coating technique on solution molarity
    (Springer, 2022) Chala, Slimane; Bdirina, Madani; Elba, Mourad; Naoui, Yassine; Benbouzid, Yazid; Taouririt, Taki Eddine; Labed, Mohamed; Boumaraf, Rami; Bouhdjar, Abdel Fodhil; Sengouga, Nouredine; Yakuphanoğlu, Fahrettin; Rahmane, Saâd
    Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating technique. Zinc acetate dihy- drate and 2-methoxyethanol were used as precursor with different molar concentrations, 0.2 M, 0.3 M and 0.6 M. The effect of precursor concentration on the structural and optical properties, transmission (T), reflection (R), optical bandgap (Eg), Urbach energy (E U ), refractive index (n), extinction coefficient (k), single-oscillator energy (E 0 ), dispersion energy (E d ), moments M −1 and M −3 , dielectric constant (ε) and optical conductivity (σ), of the ZnO thin films was studied and investi- gated. Although, the transmittance, slightly, decreased and the reflectance increased, as the molar concentration increased, the measurements showed that all samples have high transparency and low reflectivity in the visible range which make them suitable for solar cells applications. It is also found that, as the molarity increased, the ZnO thin films exhibited lower Eg and E U and higher Ed, M −1 and M −3
  • No Thumbnail Available
    Item
    The effect of doping with rare earth elements (Sc, Y, and La) on the stability, structural, electronic and photocatalytic properties of the O-termintaed ZnO surface; a first-principles study
    (Elsevier, 2018) Lahmer, Mohammed Ali
    The effect of doping with rare earth atoms (Sc, Y, and La) on the stability, structural, electronic, and photocatalytic properties of the O-terminated ZnO surface was investigated by using the first-principles method. The obtained results show that all these elements have negative formation energies for all possible values of the oxygen chemical potential, and this means that the doping process with RE atoms (RE = Sc, Y, and La) enhances the stability of this surface. Our results show also that, among all considered elements, the Sc atoms have the lowest formation energy followed by Y and La, respectively. We have also investigated the effect of the formation of a RE-VO complex on the properties of the ZnO surfaces. We find that the formation of a RE-VO complex is energetically more favored than the formation of isolated REZn defect under Zn-rich conditions. The effect of the formation of both REZn and RE-VO defects on the electronic and photocatalytic properties of the O-terminated ZnO surface was studied in details and the obtained results show that the RE-VO complex may be the origin of the photocatalytic properties enhancement of the doped surfaces. Moreover, we found that the Sc-doped surface prepared under Zn rich conditions may have the best photocatalytic properties followed by Y- and La-doped surfaces, respectively.
  • No Thumbnail Available
    Item
    Behavior of phase transition of ZnO in nanoscale of time a molecular dynamics computation
    (IOP Publishing, 2021) Chergui, Yahia; Aouaroun, Tahar; Hadley, Mark J; Chemam, Rafik; Ouatizerga, A.
    The phase transition of Zinc Oxide Wurtzite structure is investigated at the nanoscale of time using Equilibrium time of total energy in isobaric and isothermal ensemble. The calculations ran on the RAVEN supercomputer of Cardiff University employing Molecular Dynamics simulation and DL_POL_4 software, the short and long-range interatomic interactions modeled by Bukingham-Coulomb potential. In this work we used low and high range of pressure and temperature of 0-30 GPa and 40-200 GPa, and 300-500 K and 1500-3000 K respectively. Although no data about confirming phase transition using equilibrium time of total energy as our knowledge, our results are in agreement with the classical method but are still a prediction which needs experimental confirmation. This work has great importance in nanotechnology and many industrial and academic sectors
  • No Thumbnail Available
    Item
    Preparation and characteristic of low resistive zinc oxide thin films using chemical spray technique for solar cells application
    (2008) Sali, S.; Boumaour, Messaoud; Tala-Ighil, Razika
    In this paper, we present results concerning undoped and indium-doped zinc oxide (ZnO: In) thin films were grown on glass and Si substrates using the chemical spray technique. The effects of thickness (e), as well as the substrate temperature (Ts), were studied. It was revealed by X-Ray diffraction that the preferred orientation of polycrystals is along C-axis, with hexagonal wurtzite structure. Two important facts were calculated from RBS measurements: the dopant concentration throughout the film and the thickness of the films, it was found that the thickness increase with time of deposition. Under optimum deposition conditions a low resistivity and a high optical transmittance of the order of 2.8 × 10−4 Ω cm and 85 %, respectively, were obtained.
  • No Thumbnail Available
    Item
    Effect of Er3+ doping on structural, morphological and photocatalytical properties of ZnO thin films
    (IOP Publishing, 2018) Bouhouche, S.; Bensouici, F.; Toubane, Mahdia; Azizi, A.; Otmani, A.; Chebout, K.; Kezzoula, F.; Tala-Ighil, Razika; Bououdina, Mahdia
  • No Thumbnail Available
    Item
    Characterization and studying of ZnO thin films deposited by spray pyrolysis : effect of annealing temperature
    (Elsevier, 2016) Belkhalfa, H.; Ayed, H.; Hafdallah, A.; Aida, M.S.; Tala-Ighil, Razika
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item