Browsing by Author "Bouhemadou, A."

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Elastic, Electronic, Chemical Bonding and Thermodynamic Properties of the Ternary Nitride Ca4tin4: Ab Initio Predictions
(Elsevier Science inc, 2019) Boucenna, S.; Haddadi, K.; Bouhemadou, A.; Louail, L.; Soyalp, F.; Khenata, R.
In order to shed light on the unexplored properties of the ternary nitride Ca4TiN4, we report for the first time the results of an ab initio study of its structural, electronic, elastic, chemical bonding and thermodynamic properties. Calculated equilibrium structural parameters are in excellent concordance with available experimental data. Electronic properties were explored through the calculation of the energy band dispersions and density of states. It is found that Ca4TiN4 has an indirect band gap (Z-Gamma) of 1.625 (1.701) eV using LDA (GGA). Nature of the chemical bonding was studied via Mulliken population analysis and charge density distribution map. It is found that the Ca-N bond is dominantly ionic, whereas the Ti-N one is dominantly covalent. Elastic properties of both single-crystal and polycrystalline phases of the title compound were explored in details using the stain-stress approach. Analysis of the calculated elastic moduli reveals that the title compound is mechanically stable, ductile and elastically anisotropic. Temperature and pressure dependencies of the unit-cell volume, bulk modulus, heat capacities, volume thermal expansion coefficient, Gruneisen parameter and Debye temperature were investigated based on the quasiharmonic Debye model. (C) 2019 Published by Elsevier Inc.
Prediction Study of the Mechanical and Thermodynamic Properties of the (R Sm, Eu, Gd, and Tb) Compounds
(Springer/plenum Publishers, 2013) Mekkaoui, F.; Litimein, F.; Khenata, R.; Merabiha, O.; Bouhemadou, A.; Varshney, D.; Rached, D.
The structural, elastic, and thermodynamic properties of the cubic anti-perovskite (R = Sm, Eu, Gd, and Tb) compounds have been investigated using first principles full-potential augmented-plane wave plus local orbitals (FP-APW+lo) method with the generalized gradient approximation. The ground-state quantities such as the lattice parameter, bulk modulus, and its pressure derivative, as well as elastic constants are estimated. Computed equilibrium lattice constants agree well with the available experimental data. The full set of first-order elastic constants and their pressure dependence, which have not been calculated or measured yet, have been determined. The elastic moduli increase linearly with increasing pressure and satisfy the generalized elastic stability criteria for cubic crystals under hydrostatic pressure. The shear modulus, Young's modulus, and Poisson's ratio are calculated for ideal polycrystalline aggregates. The Debye temperature is estimated from the average sound velocity. From the elastic parameter behavior, it is inferred that cubic anti-perovskites are ductile in nature and that the bonding is predominantly of an ionic nature. Following the quasi-harmonic Debye model, the temperature effect on the lattice constant, bulk modulus, heat capacity, and Debye temperature is calculated reflecting the anharmonic phonon effects.
Theoretical Prediction of the Fundamental Properties for the Ternary Li2pth6 and Na2pth6
(Academic Press inc Elsevier Science, 2012) Ghebouli, M. A.; Choutri, H.; Bouarissa, N.; Ghebouli, B.; Bouhemadou, A.; Soyalp, F.; Ocak, H. Y.
Li2PtH6 and Na2PtH6 are good candidate for hydrogen storage. The structural, elastic, electronic and optical properties of Li2PtH6 and Na2PtH6 compounds have been investigated using pseudo-potential plane-wave method based on the density functional theory. Computed lattice constant and H atom positional parameter at equilibrium agree well with the available experimental data. A quadratic pressure dependence of the elastic stiffness is found. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young's modulus, Poisson's ratio, average sound velocity and Debye temperature are numerically estimated in the framework of the Voigt-Reuss-Hill approximation for Li2PtH6 and Na2PtH6 polycrystalline aggregate. The analyses of the band structure indicates that Li2PtH6 and Na2PtH6 are indirect gap semiconductors. The static dielectric constant and static refractive index are inversely proportional to the fundamental gap. (C) 2012 Elsevier Inc. All rights reserved.
Theory Study of Structural Parameters, Elastic Stiffness, Electronic Structures and Lattice Dynamics of Rbrh3 (R = Sc, Y, La and Lu)
(Elsevier Science Bv, 2012) Bouhemadou, A.; Ugur, G.; Ugur, S.; Soyalp, F.; Khenata, R.; Bin-Omran, S.
Density functional-based method has been used to investigate the systematic trends for structural parameters, elastic stiffness, lattice dynamics and thermal properties of cubic perovskite-type RBRh3 depending on the type of R atoms (R are Sc, Y, La and Lu). The structural parameters, single-crystal elastic constants, directional elastic wave velocities and their pressure dependence are calculated and analyzed in comparison with the available experimental and theoretical data. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young's modulus, Poisson's ratio, Lame's coefficients, average sound velocity. Debye temperature and thermal conductivity are predicted in the frame work of the Voigt-Reuss-Hill approximation for the polycrystalline RBRh3. The correlation between the mechanical properties and electronic structures has been discussed. Using the density-functional perturbation theory (DFPT), the phonon properties of RBRh3 (R = Sc, Y and La) are investigated for the first time. (C) 2011 Elsevier B.V. All rights reserved.