Yazar "Gasanly, N. M." seçeneğine göre listele

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    Characterization of Bi12SiO20 single crystal: understanding structural and thermal properties
    (Springer Heidelberg, 2024) Altuntas, G.; Isik, M.; Gasanly, N. M.
    This study presents a thorough examination of the structural and thermal characteristics of Bi12SiO20 crystal. X-ray diffraction (XRD) analysis was employed to investigate the crystallographic structure, while scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to ascertain morphological features and elemental composition, respectively. The XRD spectrum exhibited numerous peaks corresponding to the cubic crystalline structure. Thermal behavior was investigated through thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Within the crystal, negligible weight loss was observed up to 750 degrees C, followed by weight loss processes occurring in the temperature ranges of 750-919 degrees C and above 919 degrees C. The 2% weight loss in the range of 750-919 degrees C was associated with the decomposition process, and the activation energy of this process was found to be 199 kJ/mol considering Coats-Redfern expression. A significant weight loss was observed in the region above 919 C-o and was associated with the decomposition of the Bi12SiO20 compound and/or the melting processes of the components of the Bi12SiO20 compound. Three endothermic peaks were observed in the DTA plot. Additionally, DSC measurements conducted under varied heating rates indicated endothermic crystallization process around 348 degrees C, with an activation energy of 522 kJ/mol determined through the Kissenger equation. These findings present valuable details regarding the crystal's structural configuration, morphological attributes, and decomposition/phase transitions, thereby illuminating its potential applications across various fields.
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    Exploring Temperature-Dependent bandgap and Urbach energies in CdTe thin films for optoelectronic applications
    (Elsevier, 2024) Surucu, O.; Surucu, G.; Gasanly, N. M.; Parlak, M.; Isik, M.
    This study examines CdTe thin films deposited via RF magnetron sputtering, focusing on structural and optical properties. X-ray diffraction, Raman spectroscopy, and SEM assessed structural characteristics. Optical properties were analyzed through transmittance measurements from 10 to 300 K. Tauc plots and Varshni modeling revealed a temperature-dependent bandgap, increasing from 1.49 eV at room temperature to 1.57 eV at 10 K. Urbach energy rose from 82.7 to 93.7 meV with temperature. These results are essential for applications where temperature affects CdTe-based device performance.
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    Identification of shallow trap centers in InSe single crystals and investigation of their distribution: A thermally stimulated current spectroscopy
    (Elsevier, 2024) Isik, M.; Gasanly, N. M.
    Identification of trap centers in semiconductors takes great importance for improving the performance of electronic and optoelectronic devices. In the present study, we employed the thermally stimulated current (TSC) method within a temperature range of 10-280 K to explore trap centers in InSe crystal-a material with promising applications in next-generation devices. Our findings revealed the existence of two distinct hole trap centers within the InSe crystal lattice located at 0.06 and 0.14 eV. Through the leveraging the T-stop method, we offered trap distribution parameters of revealed centers. The results obtained from the experimental methodology employed to investigate the distribution of trap centers indicated that one of the peaks extended between 0.06 and 0.13 eV, while the other spanned from 0.14 to 0.31 eV. Notably, our research uncovers a remarkable variation in trap density, spanning one order of magnitude, for every 10 and 88 meV of energy variation. The results of our research present the characteristics of shallow trap centers in InSe, providing important information for the design and optimization of InSe-based optoelectronic devices.
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    NaBi(MoO4)2 crystal: Defect states and luminescence properties for optoelectronic applications
    (Elsevier, 2025) Isik, M.; Altuntas, G.; Gasanly, N. M.; Darvishov, N. H.
    This paper investigates the electronic and optical properties of NaBi(MoO4)2 crystal through absorbance, thermally stimulated current (TSC), and photoluminescence (PL) measurements. Absorbance analysis revealed important information about the bandgap and the degree of disorder within the material. The bandgap energy of the compound was found to be 2.94 eV. TSC measurements revealed the presence of hole defect centers and provided information regarding charge transport mechanisms. Two TSC peaks were observed at temperatures of 69.3 and 127.5 K, and the activation energies of the trap centers associated with these peaks were found to be 0.05 and 0.14 eV. Two PL peaks were observed around 487 and 536 nm corresponding to the blue and green emissions, respectively. These findings provide a comprehensive understanding the band structure of the NaBi (MoO4)2, highlighting its suitability for use in optoelectronic devices, sensors, and light-emitting applications.
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    Nanoindentation study of PbMoO4 single crystals: mechanical properties and implications for applications
    (Iop Publishing Ltd, 2025) Isik, M.; Gasanly, N. M.
    Nanomechanical properties of lead molybdate ( PbMoO 4 ) single crystal were investigated using nanoindentation measurements. The force-dependent Young's modulus and hardness of PbMoO4 along the [ 100 ] direction was determined using the Oliver-Pharr method. As the applied force increased, hardness and young modulus values decreased. This behavior was referred to the indentation size effect ( ISE ) . The force-dependent plots were analyzed using proportional specimen resistance model and true hardness value was determined as 1.84 GPa. As a result of increasing the applied force from 5 to 100 mN, the Young modulus decreased from 81.7 to 60.2 GPa. The dependencies of plastic and elastic deformation components were also reported in the present study. It was seen that plastic deformation is the dominant component. The fi ndings suggest that PbMoO4 is relatively soft material and can be considered as a promising material for mechanical and optoelectronics applications that require revealed hardness and Young's modulus values.
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    Spectroscopic ellipsometry study of linear and nonlinear optical properties of NaBi(Mo0.5W0.5O4)2 crystal
    (Springer, 2024) Isik, M.; Guler, I.; Gasanly, N. M.; Darvishov, N. H.
    In this study, linear and nonlinear optical characteristics of NaBi(Mo0.5W0.5O4)(2) crystal, a new material that may have potential for optoelectronic applications, were investigated. NaBi(Mo0.5W0.5O4)(2) single crystals were grown via the Czochralski method. Two sharp and well-defined peaks were observed in the x-ray diffraction pattern. These peaks were associated with tetragonal crystal structure. The data obtained from ellipsometer measurements was matched with a suitable optical model. This allowed for the presentation of the spectral dependence of various optical parameters like refractive index, dielectric constant, optical conductivity, extinction, and absorption coefficients in the range of 1.2-5.0 eV. As a result of studying the spectral dependence of the absorption coefficient under Tauc relationship, bandgap energy of the compound was found to be 3.20 eV. Using the spectral dependence of the dielectric function, the existence of two critical points with energy values of 3.72 and 4.44 eV was revealed. The change of the refractive index in the region under the bandgap was studied using the single oscillator model. Single oscillator and dispersion energies were determined from the analysis results. Nonlinear optical parameters of NaBi(Mo0.5W0.5O4)(2) crystal were also determined. With this study, the optical properties of the NaBi(Mo0.5W0.5O4)(2) are presented in more detail and valuable information is presented for the potential use of the material in optoelectronic devices.
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    Unveiling the application potential of PbMo0.75W0.25O4 crystal: Linear and nonlinear optical properties through ellipsometry
    (Elsevier, 2024) Isik, M.; Gasanly, N. M.
    PbMo0.75W0.25O4 compound is formed by replacing one quarter of the Mo atoms in the PbMoO4 with W atoms and has significant potential for optoelectronic applications. Optical properties of PbMo0.75W0.25O4 single crystal have been systematically investigated using ellipsometry measurements in the spectral range of 2.4-5.4 eV. The linear optical parameters, including refractive index, extinction coefficient, and absorption coefficient, were extracted from the obtained ellipsometry data. By analyzing spectral dependence of these parameters, band gap energy, critical point energy, and single effective oscillator parameters were determined. The refractive index spectrum was analyzed in the below band gap energy region by considering Cauchy and Sellmeier models. Additionally, nonlinear optical values were calculated, providing a comprehensive understanding of the optical properties of the PbMo0.75W0.25O4 single crystal. This study not only contributes to the fundamental understanding of the crystal's optical properties but also has potential implications for applications in optoelectronic devices and photovoltaics.