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3 Materials Science Poland

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Investigations of structural, elastic, electronic and thermodynamic properties of lutetium filled skutterudite LuFe4P12 under pressure effect: FP-LMTO method

100%

Boudia K. , Ameri M. , Al-Douri Y. , Ameri I. , Bouafia H.

2015

tom Vol. 33, No. 4

867--878

Structural, elastic, electronic and thermodynamic properties of ternary cubic filled skutterudite compound were calculated. We have computed the elastic modulus and its pressure dependence. From the elastic parameter behavior, it is inferred that this compound is elastically stable and ductile in nature. Through the quasi-harmonic Debye model, in which phononic effects are considered, the effect of pressure P (0 to 50 GPa) and temperature T (0 to 3000 degrees C) on the lattice constant, elastic parameters, bulk modulus B, heat capacity, thermal expansion coefficient alpha, internal energy U, entropy S, Debye temperature theta(D), Helmholtz free energy A, and Gibbs free energy G are investigated.

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

86%

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

tom 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.

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

86%

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

tom 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.