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Structural, Mechanical and Thermodynamic Properties Under Pressure Effect of Rubidium Telluride: First Principle Calculations

Bidai K., Ameri M., Ameri I., Bensaid D, Slamani A., Zaoui A., Al-Douri Y.

Archives of Metallurgy and Materials

2017

Vol. 62, iss. 2A

865--871

First-principles density functional theory calculations have been performed to investigate the structural, elastic and thermodynamic properties of rubidium telluride in cubic anti-fluorite (anti-CaF2-type) structure. The calculated ground-state properties of Rb2Te compound such as equilibrium lattice parameter and bulk moduli are investigated by generalized gradient approximation (GGA-PBE) that are based on the optimization of total energy. The elastic constants, Young’s and shear modulus, Poisson ratio, have also been calculated. Our results are in reasonable agreement with the available theoretical and experimental data. The pressure dependence of elastic constant and thermodynamic quantities under high pressure are also calculated and discussed.

FP-LAPW investigation of mechanical and thermodynamic properties of Na2X (X = S and Se) under pressure and temperature effects

Bidai K., Ameri M., Bensaid D, Moulay N. E., Al-Douri Y., Ameri I.

Materials Science Poland

2015

Vol. 33, No. 3

649--659

Structural, elastic and thermodynamic properties of sodium chalcogenides (Na2X, X = S, Se) have been calculated using FP-APW+lo method. The ground state lattice parameter, bulk moduli have been obtained. The Zener anisotropy factor, Poisson’s ratio, shear modulus, Young’s modulus, have also been calculated. The calculated structural and elastic constants are in good agreement with the available data. We also determined the thermodynamic properties, such as heat capacities Cv and Cp, thermal expansion α, entropy S, and Debye temperature ΘD, at various pressures and temperatures for Na2X compounds. The elastic constants under high pressure and temperature are also calculated and elaborated.

FP-LMTO study of structural, electronic, thermodynamic and optical properties of Mg x Cd1−x Se alloys

Bensaid D, Ameri M, El Hanani M D, Azaz Y, Bendouma D, Al-Douri Y, Ameri I

Materials Science Poland

2014

Vol. 32, No. 4

719--728

Structural, electronic and optical properties of MgxCd1−xSe (0 6 x 6 1) are calculated for the first time using density functional theory. Our results show that these properties are strongly dependent on molar fraction of particular components – x. The bond between Cd and Se is partially covalent and the covalent nature of the bond decreases as the concentration of Mg increases from 0 % to 100 %. It is found that MgxCd1−xSe has a direct band gap in the entire range of x and the band gap of the alloy increases from 0.43 to 2.46 eV with the increase in Mg concentration. Frequency dependent dielectric constants ε1(ω),ε2(ω) refractive index n(ω) are also calculated and discussed in detail. The peak value of refractive indices shifts to higher energy regions with the increase in Mg. The larger value of the extraordinary refractive index confirms that the material is a positive birefringence crystal. The present comprehensive theoretical study of the optoelectronic properties of the material predicts that it can be effectively used in optoelectronic applications in the wide range of spectra: IR, visible and UV. In addition, we have also predicted the heat capacities (CV ), the entropy (S), the internal energy (U) and the Helmholtz free energy (F) of MgxCd1−xSe ternary alloys.