Center University Of Tissemsilt

Tissemsilt, Algeria

Center University Of Tissemsilt

Tissemsilt, Algeria
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Amari S.,University of Hassiba Ben Bouali Chlef | Amari S.,University Djilali Liabes | Dahmane F.,Center University Of Tissemsilt | Dahmane F.,University of Mascara | And 5 more authors.
Journal of the Korean Physical Society | Year: 2016

In this study, the structural, magnetic and electronic properties of the Co2FeGe1−xSix(x = 0, 0.5, 1) Heusler compounds have been calculated using the full-potential linearized augmented plane-wave method based on the spin density functional theory within the generalized gradient approximation of Perdew-Burke-Ernzerhof. In order to take into account the correlation effects, we have also performed GGA + U calculations, where the Hubbard on-site Coulomb interaction correction U is calculated by using the constraint local density approximation for the Co and the Mn atoms. The Cu2MnAl-type structure is found to be energetically more favorable than the Hg2CuTitype structure for both the Co2FeSi and the Co2FeGe compounds. The calculated atomic resolved densities of states of Co2FeSi and Co2FeGe indicate nearly half-metallic behaviors with small spindown electronic densities of states at the Fermi level. This behavior is corrected by including the Hubbard Coulomb energy U term. The Coulomb exchange correlation U confirms the halfmetallic property in both the Co2FeSi and the Co2FeGe compounds. We also discuss the electronic structures, the total and the partial densities of states, and the local magnetic moments. The Co2FeGe0.5Si0.5compound shows a nearly half-metallic behavior with a small spin-down electronic density of states at the Fermi level in both the GGA and GGA+U approximations. © 2016, The Korean Physical Society.


Mokhtari M.,University of Science and Technology of Oran | Mokhtari M.,Center University Of Tissemsilt | Zekri L.,University of Science and Technology of Oran | Kaiss A.,Aix - Marseille University | Zekri N.,University of Science and Technology of Oran
Condensed Matter Physics | Year: 2016

The effect of thickness on the width of the percolation threshold in metal-dielectric composite films was examined. The distribution of current intensities through cubic networks of metal and dielectric components was determined using Kirchhoff's equations. From the tail of current distribution, the width of the percolation threshold was defined using Lévy statistics, and determined as a function of the film thickness for a system size 100. In the 2D-3D crossover region, the percolation width decreases as a power-law with a power exponent of 0.36±0.01. © M. Mokhtari, L. Zekri, A. Kaiss, N. Zekri, 2016.


Dahmane F.,Center University Of Tissemsilt | Dahmane F.,University Djilali Liabes | Mogulkoc Y.,Ankara University | Doumi B.,University Djilali Liabes | And 6 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2016

Using the first-principles density functional calculations, the structural, electronic and magnetic properties of the Fe2XAl (X=Cr, Mn, Ni) compounds in both the Hg2CuTi and Cu2MnAl-type structures were studied by the full-potential linearized augmented plane waves (FP-LAPW) method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA) where the results show that the Cu2MnAl-type structure is energetically more stable than the Hg2CuTi-type structure for the Fe2CrAl and Fe2MnAl compounds at the equilibrium volume. The full Heusler compounds Fe2XAl (X=Cr, Mn) are half-metallic in the Cu2MnAl-type structure. Fe2NiAl has a metallic character in both CuHg2Ti and AlCu2Mn-type structures. The total magnetic moments of the Fe2CrAl and Fe2MnAl compounds are 1.0 and 2.0 μB, respectively, which are in agreement with the Slater-Pauling rule Mtot=Ztot- 24. © 2016 Elsevier B.V. All rights reserved.


Bettahar N.,University Djilali Liabes | Nasri D.,Université Ibn Khaldoun | Nasri D.,Normal Superior School of Technical Education Oran | Benalia S.,University Djilali Liabes | And 8 more authors.
International Journal of Thermophysics | Year: 2013

Elastic, thermodynamic, electronic, and magnetic properties in the cubic antiperovskite InNCe3 compound are derived from the full-potential linear muffin-tin orbital method. From the computed elastic constants, theoretical values of Young's modulus, the shear modulus, Poisson's ratio, Lamé's coefficients, sound velocities, and the Debye temperature are evaluated. Analysis of the ratio between the bulk modulus and the shear modulus shows that InNCe3 is brittle in nature. The variations of elastic constants with pressure indicate that this compound possesses higher mechanical stability in the pressure range from 0 to 40 GPa. The electronic and magnetic properties of this compound are calculated by adding the Coulomb interaction U to improve the results. © 2013 Springer Science+Business Media New York.


Elahmar M.H.,University Djilali Liabes | Rached H.,University Djilali Liabes | Rached H.,University of Hassiba Ben Bouali Chlef | Rached D.,University Djilali Liabes | And 4 more authors.
Materials Science- Poland | Year: 2016

We investigated the structural stability as well as the mechanical, electronic and magnetic properties of the Full-Heusler alloy CoNiMnSi using the full-potential linearized augmented plane wave (FP-LAPW) method. Two generalized gradient approximations (GGA and GGA + U) were used to treat the exchange-correlation energy functional. The ground state properties of CoNiMnSi including the lattice parameter and bulk modulus were calculated. The elastic constants (Cij) and their related elastic moduli as well as the thermodynamic properties for CoNiMnSi have been calculated for the first time. The existence of half-metallic ferromagnetism (HM-FM) in this material is apparent from its band structure. Our results classify CoNiMnSi as a new HM-FM material with high spin polarization suitable for spintronic applications. © 2016 M.H. Elahmar et al., published by De Gruyter Open.


Bidaoui M.,CNRS Poitiers Institute of Chemistry: Materials and Natural Resources | Bidaoui M.,Blida University | Bidaoui M.,Center University Of Tissemsilt | Especel C.,CNRS Poitiers Institute of Chemistry: Materials and Natural Resources | And 5 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2015

Pt/SBA-15 catalysts, modified by zinc addition (at different Zn/Pt atomic ratios) via the co-impregnation method, were tested for the liquid phase hydrogenation of citral. The influence of the Zn insertion on the Pt monometallic catalyst properties was evaluated by different physico-chemical techniques, including X-ray diffraction, N2-physisorption, transmission electron microscopy, hydrogen chemisorption, and cyclohexane dehydrogenation as model reaction for platinum accessibility and zinc covering evaluation. On the catalysts, the hexagonal periodic structure of SBA-15 framework was maintained indicating that neither Pt and Zn impregnations, nor thermal treatments affect the organized structure of the support. A decrease of the platinum metallic accessibility was observed with the increase in the Zn concentration in the materials, which was explained, on the basis of the TEM analysis, by a poisoning of the platinum accessible sites by zinc species. For the citral hydrogenation, Pt/SBA-15 monometallic catalyst is very active, with 100% conversion obtained after 30 min reaction time, but very poorly selective in unsaturated alcohols. Zinc addition led to an inhibition of the hydrogenating activity, in agreement with the decrease of the active surface, but contributed to an increase in the selectivity to unsaturated alcohols. Selectivity in unsaturated alcohol was observed to reach a maximum of 75%, for a Zn content equal to 0.3 wt.%, that is a very interesting value if compared to performances obtained with other more classical dopant including titania and germanium. © 2015 Published by Elsevier B.V.


Zegaou B.,University Djilali Liabes | Benkhettou N.,University Djilali Liabes | Rached D.,University Djilali Liabes | Reshak A.H.,University of West Bohemia | And 3 more authors.
Computational Materials Science | Year: 2014

The electronic and magnetic properties of the ferromagnetic laves-phase GdX2 (X = Fe, Co and Ni) intermetallic compounds were calculated by using an all-electron full-potential linear muffin-tin orbital method (FP-LMTO) within GGA and GGA + U. The so-called GGA + U method is applied to properly treat the Gd-4f electron in the electronic structure calculation. The GGA improves the agreement between experiments and calculations for the lattice constants; however the GGA + U overestimates them, but gives a better representation of the band structure, density of states and magnetic moments compared to GGA alone. The reduction of the Co and Ni magnetic moments in the GdCo2 and GdNi2 compared to that in pure metals is due to the different localization strength of the transition metal and the same reason in the enormous reduction of the Curie temperatures. © 2014 Elsevier B.V. All rights reserved.


Dahmane F.,University Djilali Liabes | Mesri D.,University Djilali Liabes | Tadjer A.,University Djilali Liabes | Khenata R.,University of Mascara | And 7 more authors.
Modern Physics Letters B | Year: 2016

The structural, electronic as well as the magnetic properties of the Co2CrX (X =Al, Ga and In) full-Heusler alloy have been studied using first-principles calculations performed in the framework of density functional theory (DFT) within the generalized gradient approximation (GGA). It was taken into account both possible L21 structures (i.e. Hg2CuTi-and Cu2MnAl-type). Basically, for all compounds, the Cu2MnAl-type structure is energetically more stable than Hg2CuTi-type structure at the equilibrium volume. The electronic structure calculations for Co2CrAl reveal that half-metallic (HM) character in Cu2MnAl-type structure, Co2CrGa show nearly HM behavior and Co2CrIn has a metallic character. The predicted total magnetic moment is 3μB for Co2CrX (X =Al, Ga) which is in good convergence with the Slater-Pauling (SP) rule. © 2016 World Scientific Publishing Company.


Sabour S.,Blida University | Especel C.,CNRS Poitiers Institute of Chemistry: Materials and Natural Resources | Fontaine C.,CNRS Poitiers Institute of Chemistry: Materials and Natural Resources | Bidaoui M.,Center University Of Tissemsilt | And 4 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2016

n-Butanol oxidation was studied using noble metals (Pt, Pd, Rh and Au) supported on a highly structured mesoporous material: CMI-1. The catalysts were characterized by several physico-chemical techniques, i.e. N2 sorption, ICP, H2 chemisorption, XRD and TEM. The Pt based catalyst was the most active material, followed by Pd/CMI-1, Rh/CMI-1 and Au/CMI-1. Difference in size of the particles was proposed as origin of these results, this parameter being well-known to strongly influence the catalytic activity. The comparison of two Pt/CMI-1 catalysts prepared from various precursor salts (with and without chlorine) showed that n-butanol oxidation was sensitive to the nature of the metallic salt. Finally the modifications induced by the nature of the support were studied by comparing Pt/Al2O3 and Pt/TiO2 systems. Pt dispersion and specific surface area of the support seemed to be important parameters influencing the activity of the materials. In the studied conditions, Pt/CMI-1 was still the most active catalyst. © 2016 Elsevier B.V. All rights reserved.


Zebbar S.,University Djilali Liabes | Zebbar D.,Center University Of Tissemsilt | Kadoun A.,University Djilali Liabes
Energy Procedia | Year: 2015

This paper deals with the gaseous cascade amplification in He-H2O mixture in an ESEM. It is shown that such a mixture has the same behavior and gas amplification gain slightly modified with the increase of the (pd) parameter as compared to pure Helium. The use of the mixture gives rise to higher gain with respect to water vapor and more efficiency in the electrical neutralization of the specimen surface compared to He. All in all, the mixture exhibits high Townsend ionization coefficient, high gain and low operating voltage, which allows an expected increase of the signal to noise ratio. © 2015 The Authors. Published by Elsevier Ltd. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

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