Suleyman Cabuk

Cukurova University, Adhanah, Adana, Turkey

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Publications (12)8.99 Total impact

  • Ulas Koroglu, Suleyman Cabuk, Engin Deligoz
    Solid State Sciences. 01/2014;
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    S. Cabuk, H. Akkus, A.M. Mamedov
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    ABSTRACT: The energy band structures, density of states (DOS) and the optical properties of paraelectric cubic crystal KTaO3 have been calculated by the first principle pseudopotential using density functional theory in its local density approximation. The calculated band structure shows a direct band gap of 2.987 eV at the Γ point in the Brillouin zone. The real and imaginary parts of the dielectric function and hence the optical constants such as εeff (the optical dielectric constant) and Neff (the effective number of electrons) per unit cell are calculated. The calculated spectra are compared with the experimental results for KTaO3 and are found to be in good agreement with the experimental results.
    Physica B Condensed Matter 04/2013; · 1.33 Impact Factor
  • Suleyman Cabuk
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    ABSTRACT: The nonlinear optical properties of some ABO3 materials (BaTiO3, KNbO3, LiTaO3 and LiNbO3) are studied by density functional theory (DFT) in the local density approximation (LDA) expressions based on first-principle calculations. Our goals are to give the details of the calculations for linear and nonlinear optical properties, including the linear electro-optic (EO) tensor for some ABO3 structures with oxygen octahedral structures using first-principles methods. These results can then be used in the study of the physics of ferroelectrics, specifically, we present calculations of the second harmonic generation response coefficient X ijk (2) (−2ω, ω, ω) over a large frequency range for ABO3 crystals. The electronic linear EO susceptibility X ijk (2) (−ω, ω,0) is also evaluated below the band gap. These results are based on a series of the LDA calculations using DFT. Results for X ijk (2) (−ω, ω,0) are in agreement with experiments below the band gap. The results are compared with the theoretical calculations and the available experimental data. Keywordsoptical susceptibility–electro-optic tensor–ferroelectric–density functional theory
    Central European Journal of Physics 01/2011; 10(1):239-252. · 0.91 Impact Factor
  • E. Ece Eyi, Suleyman Cabuk
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    ABSTRACT: Ab initio calculations were performed of the structural, electronic and optical properties of the cubic ( , tetragonal ( , and orthorhombic ( ) phases of NaTaO3 using a plane-wave pseudopotential method within the density-functional theory. Results are presented for the structural properties, electronic band structure, density of states and imaginary and real parts of the frequency-dependent linear optical response. Cubic and tetragonal NaTaO3 both have an indirect band gap, at the R–Γ and Z–Γ points, respectively, whereas, orthorhombic NaTaO3 has a direct band gap at the Γ–Γ point. The optical properties of NaTaO3 were investigated by ab initio calculation under the scissor approximation. The real and imaginary parts of the dielectric function and, hence, the optical constants (such as absorption coefficient and the electron energy-loss spectrum) were calculated. This is the first quantitative theoretical prediction of optical properties, except for absorption of the orthorhombic phase, of the NaTaO3 compound.
    Philosophical Magazine 07/2010; 90(21):2965-2976. · 1.60 Impact Factor
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    AKKUS H, CABUK S, MAMEDOV M. A
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    ABSTRACT: We present a first principles calculations of the second-order optical response functions as well as the dielectric function for ABO3 (A=K, Li, Ba; B=Ti, Ta, Nb) and A5B6C7 ( A=Sb; B=S, Se; C=I, Br ) ferroelectrics. Specially, we evaluate the dielectric function ( ) ( ) ( ) 1 2 ε ω =ε ω −iε ω and the second harmonic generation response coefficient χ (2) (−2ω, ω, ω, ω) over a large frequency range. The electronic linear electro-optic susceptibility χ (2) (−ω, ω, ω, 0) is also evaluated below band gap. These results are based on the series of self-consistent LDA calculations within DFT.
    International Journal of Nanoelectronics and Materials. 01/2010; 3.
  • Suleyman Cabuk, Sevket Simsek
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    ABSTRACT: The linear and nonlinear optical (NLO) properties of the paraelectric and ferroelectric (FE) phases of lithium tantalate crystals were calculated using a first-principles approach based on density functional theory with the generalized gradient approximation. We present our results for the structural parameters, the imaginary and real parts of the frequency-dependent linear optical response, optical functions such as the spectral reflectivity, the absorption coefficient and the electron energy-loss spectrum. A simple scissors operator is applied to adjust the energy gap from calculations to match the experimental value. In the FE phase, we also study the NLO susceptibilities and calculate the NLO susceptibility tensor. LiTaO3 displays a good NLO effect. The results are compared with the theoretical calculations and available experimental data.
    Physica Scripta 01/2010; 81(5). · 1.03 Impact Factor
  • Suleyman Cabuk
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    ABSTRACT: Ab initio calculations have been performed to investigate the behaviour under hydrostatic pressure of the structural and electronic properties, the optical dielectric constant, the Born effective charges, and elastic and dynamical properties in cubic perovskite KTaO3. These physical properties have been calculated within the local density approximation in the frame of density functional theory. The results for the pressure behaviour of these properties of KTaO3 are in agreement with experimental data when available; in other cases they may be considered as predictions.
    physica status solidi (b) 11/2009; 247(1):93 - 97. · 1.49 Impact Factor
  • SULEYMAN CABUK, AMIRULLAH MAMEDOV
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    ABSTRACT: The new method of Argand diagram was used to study the optical properties and energy spectra of Gd2(MoO4)3. The results were used to calculate the number, energy position, force and relaxation time for oscillators which constructs the energy spectra of Gd2(MoO4)3. The number of oscillators and their resonance energies were determined by using Argand diagram method.
    Ferroelectrics 01/2004; 307(1):19-23. · 0.42 Impact Factor
  • Suleyman Cabuk, Amirullah M. Mamedov
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    ABSTRACT: In seeking an explanation of the mechanism for recording multivariate optical signal in PROM type systems (where the active layer is a sensitive electrooptical material) we have been studying conditions of the creation and destruction of the electret states in some ferroelectrics (LiNbO3 and Ba2NaNb5O15) with barrier and insulating contacts. The field, temperature, concentration and time dependence of the electret states and the main characteristics of traps responsible for electret states were determined. The results have been explained on the assumption that either with a decrease in temperature, the traps are partly converted into recombination centers, or the traps have a barrier and their occupation is a function of temperature.
    Ferroelectrics 12/2003; 296(1):117-125. · 0.42 Impact Factor
  • Suleyman Cabuk, Sevket Simsek
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    ABSTRACT: The electronic energy-band structure, density of states (DOS), and optical properties of AgBO3 in the paraelectric cubic phase have been studied by using density functional theory within the local density approximation for exchange-correlation for the first time. The band structure shows a band gap of 1.533 eV (AgNbO3)and 1.537 eV (AgTaO3)at (M-⌈)point in the Brillouin zone. The optical spectra of AgBO3 in the photon energy range up to 30 eV are investigated under the scissor approximation. The real and imaginary parts of the dielectric function and — thus the optical constants such as reflectivity, absorption coefficient, electron energy-loss function, refractive index, and extinction coefficient — are calculated. We have also made some comparisons with related experimental and theoretical data that is available.
    Central European Journal of Physics 6(3):730-736. · 0.91 Impact Factor
  • Ulas Koroglu, Suleyman Cabuk, Engin Deligoz
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    ABSTRACT: We present a study of the structural, electronic, elastic and vibrational properties of the rhombohedral BiAlO3 structure within the local density approximation of density functional theory using norm-conserving pseudopotentials. The calculated equilibrium lattice constant, angle and atomic position are in reasonable agreement with the available experimental and theoretical dates. Based on the elastic constants and their related parameters, the crystal mechanical stability have been discussed. The elastic constants for BiAlO3 are also needed to completely determine its elastic properties including polycrystalline bulk, shear and Young’s moduli, Poisson’s ratio and the elastic anisotropy. Energy band structure shows that the rhombohedral BiAlO3 has an indirect band gap between D and Г-D symmetry points. We compute Born effective charge tensor, which is found to be quite anisotropic of Bi and O atoms. BiAlO3 have been studied by applying the direct method and deriving the phonon dispersion relations which include the longitudinal/transverse optical phonon mode splitting. In the rhombohedral phase the phonon dispersion curves show a soft mode between X and Г-point. This soft mode leads to the observed rhombohedral-cubic phase transition. The results are compared with the previous calculations and available experimental data.
    Journal of Alloys and Compounds. 574:520–525.
  • Gulden Celik, Suleyman Cabuk
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    ABSTRACT: Electronic and optical properties of Sr(Ti,Zr)O3 crystals in the cubic (Pm-3m) and tetragonal (I4/mcm) phase were calculated by the first-principles calculations using the density functional theory and the local density approximation. The band structure of cubic and tetragonal phases show an indirect band gap at (R-Γ) point and at (M-Γ) point in the Brillouin zone, respectively. The linear photon-energy dependent dielectric functions and some optical properties such as the absorption coefficient, energy-loss function and reflectivity are calculated for both phases. The optical properties of tetragonal phase of Sr(Ti,Zr)O3 were investigated by theoretical methods for the first time. We have also made some comparisons with the available related experimental and theoretical data.
    Central European Journal of Physics 11(3). · 0.91 Impact Factor