• R AHMED

      Articles written in Bulletin of Materials Science

    • Structural, elastic, optoelectronic and magnetic properties of CdHo$_2$S$_4$ spinel: a first-principle study

      I HATRAF O MERABIHA T SEDDIK H BALTACHE R KHENATA R AHMED SALEEM A KHAN A BOUHEMADOU SIKANDER AZAM S BIN OMRAN

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      We report the results of the full-potential linearized augmented plane wave (FP-LAPW) calculations on the structural, elastic, optoelectronic and magnetic properties of CdHo$_2$S$_4$ spinel. Both the generalized gradient approximation (GGA) and Trans-Blaha modified Becke-Johnson potential (TB-mBJ) are used to model the exchange-correlation effects. The computed lattice parameter, internal coordinate and bulk modulus are in good agreement with the existing experimentaldata. According to the calculated elastic moduli, CdHo$_2$S$_4$ is mechanically stable with a ductile nature and a noticeableelastic anisotropy. The ferromagnetic phase of CdHo2S4 is energetically favourable compared to non-magnetic one, with ahigh magnetic moment of about 8.15 $\mu$B. The calculated band structure demonstrates that the title compound is a direct bandgap semiconductor. The TB-mBJ yields a band gap of $\sim$1.86 and $\sim$2.17 eV for the minority and majority spins, respectively.The calculated optical spectra reveal a strong response in the energy range between the visible light and the extreme UVregions.

    • First-principles computations of Y$_x$Ga$_{1−x}$As-ternary alloys: a study on structural, electronic, optical and elastic properties

      S TOUAM R BELGHIT R MAHDJOUBI Y MEGDOUD H MERADJI MUHAMMAD SHEHRYAR KHAN R AHMED R KHENATA S GHEMID D P RAI Y AL-DOURI

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      In this work, the first-principles computational study on the structural, elastic, electronic and optical propertiesof Y$_x$Ga$_{1−x}$As as a function of yttrium concentration ($x$) is presented. The computations are performed using the fullpotential linearized augmented plane wave plus local orbital method designed within density functional theory. Firstly,we performed our calculations on the most stable phases, NaCl and zinc blende, then their transition pressure for eachconcentration is determined and analysed. Our computed results for the zero yttrium concentration are found consistentwith the available experimental measurements as well as with theoretical predictions. Moreover, the dependencies of theseparameters upon yttrium concentration ($x$) were found to be non-linear.We also report computed results on electronic-bandstructure, electronic energy band gap results and density of states. A systematic study on optical properties to analyse itsoptoelectronic character and elastic properties is presented.

    • Insight view of mechanical, electronic and thermodynamic properties of the novel intermetallic REPt$_4$In$_4$ (RE $=$ Eu, Gd, Tb, Dy, Ho) compounds via ab initio calculations

      M Z BOUAYED A YAKOUBI R AHMED H KHACHAI R KHENATA S H NAQIB M M OBEID H R JAPPOR S J EDREES S BIN OMRAN XIAOTIAN WANG

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      In this study, the full potential linearized augmented plane wave method with the GGA approximation was employed to study the structural, elastic, electronic and thermal properties of the novel intermetallic REPt$_4$In$_4$ (RE$=$Eu,Gd, Tb, Dy, Ho) compounds. Our findings demonstrate that the equilibrium lattice parameters are in good agreement with the available experimental measurements. The elastic constants ($C_{\rm ij}$) were also calculated to understand the mechanical properties and structural stability of the compounds. Furthermore, the density of states and the charge density distributionsof the compounds were calculated to understand the nature of the bonding in the material. Our analysis of the calculated values of the Poisson’s ratio and the $B/G$ ratio shows their ductile structure. Additionally, the temperature-dependent thermodynamic parameters are computed by the quasi-harmonic Debye model in the range of 0–600 K, where the primitive cell volume and thermal expansion coefficients have been obtained successfully. Consequently, this study on the structural, elastic, bonding and thermal properties of REPt$_4$In$_4$ intermetallic compounds demonstrate that these compounds can be used as potential candidates in the domain of energy storage and electronic devices.

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