Yazar "Goumri-Said, Souraya" seçeneğine göre listele

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  • Küçük Resim
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    Ab initio investigations of the strontium gallium nitride ternaries Sr3GaN3 and Sr6GaN5: promising materials for optoelectronic
    (IOP PUBLISHING LTD, 2013) Goumri-Said, Souraya; Özışık, Hacı; Deligöz, Engin; Kanoun, Mohammed Benali
    Sr3GaN3 and Sr6GaN5 could be promising potential materials for applications in the microelectronics, optoelectronics and coating materials areas of research. We studied in detail their structural, elastic, electronic, optical as well as the vibrational properties, by means of density functional theory framework. Both of these ternaries are semiconductors, where Sr3GaN3 exhibits a small indirect gap whereas Sr6GaN5 has a large direct gap. Indeed, their optical properties are reported for radiation up to 40 eV. Charge densities contours, Hirshfeld and Mulliken populations, are reported to investigate the role of each element in the bonding. From the mechanical properties calculation, it is found that Sr6GaN5 is harder than Sr3GaN3, and the latter is more anisotropic than the former. The phonon dispersion relation, density of phonon states and the vibrational stability are reported from the density functional perturbation theory calculations.
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    Electronic structure and related optical, thermoelectric and dynamical properties of Lilianite-type Pb7Bi4Se13: Ab-initio and Boltzmann transport theory
    (Elsevier B.V., 2020) Azam, Sikander; Goumri-Said, Souraya; Khan, Saleem Ayaz; Özışık, Hacı; Deligöz, Engin; Kanoun, Mohammed Benali; Khan, Wilayat
    The electronic, optical, thermoelectric, and dynamic properties of Pb 7 Bi 4 Se 13 have been investigated using first principles calculations. The existence of heavy elements, bismuth and lead, has required to consider the spin–orbit coupling as implemented in the second variational procedure. It was observed that the upper of the valence band region appears predominantly from Se-p states with an admixture of Bi- p and Pb- p states, while the CBM comes mainly from Bi- p states only. The calculated optical properties illustrate a small manifold direct and indi- rect inter-band transitions emerging in the visible region. Semi classic Boltzmann theory was then employed to determine the Seebeck coefficient, electrical conductivity, thermal conductivity, and power factor. The phonon dispersion curve has been computed and explained. It can be deduced that the slight structural instability ob- served from phonon calculations is related to lower lattice thermal conductivity. Our findings were compared with the available experimental measurements, showing a good agreement.
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    Revisiting the electronic structures and phonon properties of thermoelectric antimonide-tellurides: spin–orbit coupling induced gap ppening in ZrSbTe and HfSbTe
    (MDPI AG, 2021) Goumri-Said, Souraya; Alrebdi, Tahani A.; Deligöz, Engin; Özışık, Hacı; Kanoun, Mohammed Benali
    We report theoretical studies based on density functional theory within spin-orbit coupling to explore electronic structures, lattice dynamical properties of ZrSbTe and HfSbTe. With spin?orbit coupling included, our findings reveal that ZrSbTe and HfSbTe exhibit a semiconducting behavior with narrow indirect band gaps of 0.10 eV, and 0.15 eV, respectively. Besides, the lattice dynamical properties revealed that the explored materials based on antimonide?tellurides are dynamically stable. On the basis of electronic structures, the thermoelectric properties were computed using the Landauer-Buttiker formula by considering both electron and phonon contributions in the transport properties calculation. We employed Green’s-function method based on the Green-Kubo-Mori formula, where the thermoelectric properties such as the electrical conductivity ? and thermopower ? were estimated in terms of the correlation functions. The present work could be viewed as a significant amendment of the electronic nature of ZrSbTe and HfSbTe that were reported to be metallic in literature.
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    Stability and morphology-dependence of Sc3+ ions incorporation and substitution kinetics within ZnO host lattice
    (ELSEVIER SCI, 2015) Yumak, Ayşe; Turgut, Güven; Kamoun, Olfa; Özışık, Hacı; Deligöz, Engin; Petkova, Petya; Mimouni, Refka; Boubaker, Karem; Amlouk, Mosbah; Goumri-Said, Souraya
    In this study, sol-gel spin coating route was carried out to prepare Scandium doped ZnO thin films with different controlled percentage (1-7%). Particularly, it has been demonstrated, through original conjoint morphological-structural and optical investigations, that some interesting physical properties were induced. Indeed, X-ray diffraction (XRD) analysis shows that (002) preferential crystalline plane for Sc doped ZnO films was kept along with ZnO hexagonal wurtzite structure, although Sc doping seemed to cause a decrease in crystallinity. Except for 1 at% Sc doping ratio, optical band gap changes reversely with Urbach energy with a decrease in optical gap and a broadening of the absorption tail. Ab-initio calculations of lattice dynamical properties outlined additional strong hybridization between Sc and O atoms and show the stability of Scandium doped ZnO.