• H Meradji

      Articles written in Bulletin of Materials Science

    • First principles calculations of structural, electronic and thermal properties of lead chalcogenides PbS, PbSe and PbTe compounds

      N Boukhris H Meradji S Amara Korba S Drablia S Ghemid F El Haj Hassan

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      The structural, electronic and thermal properties of lead chalcogenides PbS, PbSe and BeTe using full-potential linear augmented plane wave (FP-LAPW) method are investigated. The exchange–correlation energy within the local density approximation (LDA) and the generalized gradient approximation (GGA) are described. The calculated structural parameters are in reasonable agreement with the available experimental and theoretical data. The electronic band structure shows that the fundamental energy gap is direct (L–L) for all the compounds. Thermal effects on some macroscopic properties of these compounds are predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variations of the lattice constant, bulk modulus, heat capacity, volume expansion coefficient and Debye temperature with temperature and pressure are obtained successfully. The effect of spin–orbit interaction is found to be negligible in determining the thermal properties and leads to a richer electronic structure.

    • First-principle calculations of the structural, electronic, thermodynamic and thermal properties of ZnSxSe1−x ternary alloys

      S Bendaif A Boumaza O Nemiri K Boubendira H Meradji S Ghemid F El Haj Hassan

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      First-principle calculations were performed to study the structural, electronic, thermodynamic and thermal properties of ZnSxSe1−x ternary alloys using the full potential-linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT). In this approach the Wu–Cohen generalized gradient approximation (WC-GGA) and Perdew–Wang local density approximation (LDA) were used for the exchange–correlation potential. For band structure calculations, in addition to WC-GGA approximation, both Engel–Vosko (EV-GGA) generalized gradient approximation and recently proposed modified Becke–Johnson (mBJ) potential approximation have been used. Our investigation on the effect of composition on lattice constant, bulk modulus and band gap for ternary alloys shows a linear dependence on alloy composition with a small deviation. The microscopic origins of the gap bowing were explained using the approach of Zunger and co-workers. Besides, a regular-solution model was used to investigate the thermodynamic stability of the alloys which mainly indicates a phase miscibility gap. Finally, the quasi-harmonic Debye model was applied to see how the thermal properties vary with temperature at different pressures.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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