Browsing by Author "Z. Charifi"

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    Effect of octahedral cation on electronic, magnetic and optic properties of CoX2O4 (X = Cr, Mn and Fe) spinel compound
    (UNIVERSITE MSILA, 2022) N. Hetache; Z. Charifi; T. Ghellab; H. Baaziz; F. Soyalp
    The GGA+U approximation is used to compute the magnetic, structural, and optical and electronic properties of CoX2O4 (X = Cr, Mn and Fe) spineles. For these spineles, X has an effect on their behavior.The problem of the relationship between the relative forces of the exchange effect and the crystal field effect was investigated via a comprehensive examination of the densities of electronic states in order to get a better understanding of the electronic aspect of these compounds.It is only by the introduction of electron-electron interactions between magnetic cations that it is feasible to get the correct ground state. Changing the X cations causes a complete shift in the crystalline structure, which goes from cubic normal spinel for CoFe2O4 to tetragonal normal spinel for CoMn2O4 to inverse spinel for CoCr2O4.While our spineles exhibit considerable differences in their electronic behavior, an increase in the band gap from Fe to Mn and Cr compounds has been seen in our spineles. The occupancy of sub-lattices in the inverse phase of CoFe2O4 and the presence of severe structural distortion in the CoMn2O4 compound have a major impact on magnetic exchange interactions.In order to predict the trends of magnetic exchange couplings, it is necessary to analyze structural characteristics as well as electronic structures. Because the iron states in CoFe2O4 are tightly confined, this spinel differs significantly from the X cation states in the other two spinels, as shown by our observations. The change in X cations thus enables us to validate the trend in the characteristics of CoX2O4that has been observed.Prediction of optical characteristics is achievable, and we were able to compute a variety of optical parameters using this method. We've found that the value of  1 0 lowers as the band gap increases.
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    Properties of the double half-heusler alloy ScNbNi2Sn2 with respect to structural, electronic, optical, and thermoelectric aspects
    (2023) H. Mekki; H. Baaziz; Z. Charifi; A.E. Genç; S. Ugur; G. Ugur
    In the current work, the structural, electronic, thermoelectrics, and optical characteristics of the double half Heusler (DHH) ScNbNi2Sn2 compound are reported for the first time using density functional theory (DFT). The computed band structures show typical semiconductor behavior with an indirect bandgap (0.47 eV) using EV GGA approximation. We also investigated the optical properties such as the dielectric function, optical con ductivity, refractive index. Boltzmann’s semiclassical theory attempts to explain a simulation concept in the BoltzTrap software, and the findings were presented and analyzed in terms of electrical conductivity, electronic and lattice thermal conductivities, the Seebeck coefficient, and the Figure of merit over a 50 K–1000 K tem perature range. At room temperature, with a low magnitude of lattice thermal conductivity (κL) (5.30776 W/m. K) and a maximum value of the merit factor (ZT) is 0.64 at 900 K for ScNbNi2Sn2 compound is observed. These findings suggest that our material may be a viable option for use in high-temperature thermoelectric devices. We calculated (S, (σ /τ), (ke /τ)) along the x, y, and z axes utilizing the EV-GGA method. We found out that our compound is thermoelectrically anisotropic. We have also studied in EV-GGA the effect of the carrier concen tration on the Seebeck coefficnet at T = 600 K. The maximum value of S is 356.9905 μV/K with n = 3.04 × 1019Cm− 3 within GGA and EV-GGA respectively