Wyniki wyszukiwania - Biblioteka Nauki

1

Structural properties of Sb- and Te-based binary compounds: Spin-orbit effect

100%

Al-Douri Y.

Materials Science Poland

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2013

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tom Vol. 31, No. 1

133-138

EN

The band structure of AlSb, GaSb, ZnTe and CdTe is calculated using the empirical pseudopotential method (EPM) coupled with spin-orbit (SO) splitting. We applied our empirical model of bulk modulus with SO effect. It has been noticed that SO has a crucial effect on the band structure of these compounds but does not in?uence the structural phase transition. The calculated results are in good agreement with the experimental data.

2

Tribological properties of DLC and GLC coating for automotive engine components application under lubrication

63%

Al-Samarai R. A. , Al-Douri Y.

International Journal of Applied Mechanics and Engineering

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2023

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tom Vol. 28, no. 4

10--25

EN

Modern automotive designs are needed to increase mechanical and thermal loads that have longer lifespans and are lighter. The power transmissions and motors often use low-friction hard coatings to prevent wear and reduce friction. The Cr-doped graphite-like carbon method is employed for evaluating coating friction and responses to chromium-doped graphite-like carbon (Cr-GLC) under lubrication. Cr-GLC coatings and chromium-doped diamond-like carbon (Cr-DLC) coatings are arranged using physical vapor deposition (PVD) and plasma-enhanced chemical vapor deposition (PECVD), respectively. The results have demonstrated in comparison to the dry friction coefficient, the friction coefficient under lubrication conditions has been reduced by 40%. Due to its excellent frictional physicochemical properties and compact microstructure, Cr-DLC has an optimum tribological resistance that is significantly higher than that of Cr-GLC. Viscosity, corrosivity, and coating microstructure are used to measure the impact of composite elements. The most ideal characteristics of the Cr-GLC coating are attributed to the non-reaction of additives in oil with friction surfaces.

3

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

45%

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

Materials Science Poland

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2015

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tom Vol. 33, No. 4

867--878

EN

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.

4

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

38%

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

Materials Science Poland

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2015

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tom Vol. 33, No. 3

649--659

EN

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.

5

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

38%

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

Materials Science Poland

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2014

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tom Vol. 32, No. 4

719--728

EN

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.

6

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

38%

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

Archives of Metallurgy and Materials

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2017

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tom Vol. 62, iss. 2A

865--871

EN

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.

7

Predictive study of structural, electronic, magnetic and thermodynamic properties of XFeO3 (X = Ag, Zr and Ru) multiferroic materials in cubic perovskite structure: first-principles calculations

38%

Moulay N. , Ameri M. , Azaz Y. , Zenati A. , Al-Douri Y. , Ameri I.

Materials Science Poland

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2015

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tom Vol. 33, No. 2

402--413

EN

The full potential linear-muffin-tin-orbital method within the spin local density approximation has been used to study the structural, electronic, magnetic and thermodynamic properties of three multiferroic compounds of XFeO3 type. Large values of bulk modulus for these compounds have been obtained, which demonstrates their hardness. The calculated total and partial density of states of these compounds shows a complex of strong hybridized 3d and 4d states at Fermi level. The two degenerate levels e(g) and t(2g) clearly demonstrate the origin of this complex. We have also investigated the effect of pressure, from 0 GPa to 55 GPa, on the magnetic moment per atom and the exchange of magnetic energy between the ferromagnetic and antiferromagnetic states. For more detailed knowledge, we have calculated the thermodynamic properties, and determined heat capacity, Debye temperature, bulk modulus and enthropy at different temperatures and pressures for the three multiferroic compounds. This is the first predictive calculation of all these properties.

8

Structural and elastic properties of TiN and AlN compounds: first-principles study

38%

Fodil M. , Mounir A. , Ameri M. , Baltache H. , Bouhafs B. , Al-Douri Y. , Ameri I.

Materials Science Poland

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2014

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tom Vol. 32, No. 2

220--227

EN

First-principles calculations of the lattice constants, bulk modulus, pressure derivatives of the bulk modulus and elastic constants of AlN and TiN compounds in rock-salt (B1) and wurtzite (B4) structures are presented. We have used the fullpotential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT) in the generalized gradient approximation (GGA) for the exchange-correlation functional. Moreover, the elastic properties of cubic TiN and hexagonal AlN, including elastic constants, bulk and shear moduli are determined and compared with previous experimental and theoretical data. Our results show that the structural transition at 0 K from wurtzite to rock-salt phase occurs at 10 GPa and -26 GPa for AlN and TiN, respectively. These results are consistent with those of other studies found in the literature.

9

Fabrication of Cu2O nanostructured thin film by anodizing

32%

Voon C. H. , Lim B. Y. , Gopinath S. C. B. , Al-Douri Y. , Foo K. L. , Md Arshad M. K. , Ten S. T. , Ruslinda A. R. , Hashim U. , Tony V. C. S.

Materials Science Poland

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2018

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tom Vol. 36, No. 2

209--216

EN

Cuprous oxide, a narrow bandgap p-type semiconductor, has been known as a potential material for applications in supercapacitors, hydrogen production, sensors, and energy conversion due to its properties such as non-toxicity, easy availability, cost effectiveness, high absorption coefficient in the visible region and large minority carriers diffusion length. In this study, Cu2O nanostructured thin film was fabricated by anodizing of Cu plates in ethylene glycol containing 0.15 M KOH, 0.1 M NH4F and 3 wt.% deionized water. The effects of anodizing voltage and temperature of electrolyte were investigated and reported. It was found that nanoporous Cu2O thin film was formed when anodizing voltages of 50 V and 70 V were used while a dense Cu2O thin film was formed due to the aggregation of smaller nanoparticles when 30 V anodizing voltage was used. Nanoplatelets thin film was formed when the temperature of electrolyte was reduced to 15 °C and 5 °C. X-ray diffraction confirmed the presence of Cu2O phase in thin film formed during anodizing of Cu plates, regardless of the anodizing voltage and temperature of electrolyte. Photoluminescence spectroscopy showed the presence of Cu2O peak at 630 nm corresponding to band gap of 1.97 eV. A mechanism of the formation of Cu2O thin film was proposed. This study reported the ease of tailoring Cu2O nanostructures of different morphologies using anodizing that may help widen the applications of this material.

10

Ab initio calculations of structural, elastic, electronic and thermodynamic properties of the cerium filled skutterudite CeRu4P12 under the effect of pressure

32%

Berrahal M. , Ameri M. , Al-Douri Y. , Hashim U. , Varshney D. , Ameri I. , Boubchir M. , Abderrahim B.

Materials Science Poland

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2015

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tom Vol. 33, No. 4

699--708

EN

The paper presents an investigation on crystalline, elastic and electronic structure in addition to the thermodynamic properties for a CeRu4P12 filled skutterudite device by using the full-potential linear muffin-tin orbital (FP-LMTO) method within the generalized gradient approximations (GGA) in the frame of density functional theory (DFT). For this purpose, the structural properties, such as the equilibrium lattice parameter, bulk modulus and pressure derivatives of the bulk modulus, were computed. By using the total energy variation as a function of strain we have determined the independent elastic constants and their pressure dependence. Additionally, the effect of pressure P and temperature T on the lattice parameters, bulk modulus, thermal expansion coefficient, Debye temperature and the heat capacity for CeRu4P12 compound were investigated taking into consideration the quasi-harmonic Debye model.