Yazar "Kurucay, Ali" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • Küçük Resim Yok
    Öğe
    Analysing the impact of Dy dopants on Zn-based hydroxyapatites: modelling and characterization perspectives
    (Indian Acad Sciences, 2024) Buyuk, Oznur; Bulut, Niyazi; Temuz, M. mursit; Orek, Cahit; Ates, Tankut; Kaygili, Omer; Kurucay, Ali
    This study is aimed to investigate the effects of introducing dysprosium (Dy) into Zn-based hydroxyapatite (HAp) at various concentrations (0.45, 0.90, 1.35 and 1.80%). The structural and optical properties of pure and doped HAp were thoroughly examined through theoretical and empirical analyses, including X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) studies. The results confirmed the successful incorporation of Dy into the HAp lattice without significantly affecting its thermal stability or stoichiometry. The introduction of Dy into Zn-based HAp led to notable alterations in several material parameters. The lattice parameters, crystallinity, lattice stress, strain and anisotropic energy density varied with different Dy concentrations. In comparison with undoped HAp, all Dy-doped Zn-based HAps exhibited reduced crystallite size values, indicating a change in the microstructure. Furthermore, the material density increased from 3.159 to 3.228 g cm-3 with Dy doping. The band gap (BG), an important parameter for optical applications, is consistently decreased from 4.6 to 3.9 eV as the Dy concentration increased. This decrease in BG suggests the potential for improved photocatalytic or optoelectronic properties in Dy-doped Zn-based HAp. Additionally, the linear absorption coefficient (LAC) increased, indicating enhanced light absorption. Overall, this study provides a comprehensive understanding of structural and optical modifications induced by Dy doping in Zn-based HAp. These findings contribute to the potential application of Dy-doped Zn-based HAp in various fields, including biomedicine, photocatalysis and optoelectronics.
  • Küçük Resim Yok
    Öğe
    Experimental and theoretical characterization of Bi-based hydroxyapatites doped with Ce
    (Elsevier Sci Ltd, 2022) Kareem, Rebaz Obaid; Kaygili, Omer; Ates, Tankut; Bulut, Niyazi; Koytepe, Suleyman; Kurucay, Ali; Ercan, Ismail
    This study deals with the theoretical and experimental characterizations of Bi-based hydroxyapatites (HAps) codoped with Ce. Five samples of Bi-based HAp (at a constant amount of 0.125 at.%) with additions of the Ce in various amounts (0, 0.125, 0.25, 0.375, and 0.500 at. %) were synthesized by using the wet chemical method. The prepared samples were investigated experimentally by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). All the samples were also modeled by using a density functional theory (DFT), and theoretical results were obtained. Both experimental and theoretical results showed that the lattice parameters and unit cell volume were significantly affected by Ce content. Calculated bandgap energy results of the samples gradually reduced from 4.6308 eV to 4.5299 eV. The bandgap decreased with increasing Ce content, and the densities of states (DOS) values were also affected by the amount of Ce. It was found that the sample doped with 0.500 at. % Ce showed the best biocompatibility among all the as-synthesized samples. The linear absorption coefficient increased with increasing amounts of Ce in all samples, while this parameter decreased with increasing photon energy. The density increases with the increasing Ce content ranging from 3.1615 g cm-3 to 3.1772 g cm- 3. Both crystallite size and crystallinity decreased gradually with the increasing amount of Ce. FTIR and Raman spectra confirm the formation of the HAp structure for all the samples.
  • Küçük Resim Yok
    Öğe
    Sr/Smco-doped hydroxyapatites: experimental characterization and theoretical research
    (Springer, 2022) Hssain, Ala Hamd; Bulut, Niyazi; Ates, Tankut; Koytepe, Suleyman; Kurucay, Ali; Kebiroglu, Hanifi; Kaygili, Omer
    This paper goes into extensive detail about the theoretical and experimental characterization of Sr doped hydroxyapatite (HAp) samples that have been doped with Sm in various amounts. To accomplish this, five HAps containing a constant 0.133at.% of Sr were additionally doped with Sm at varied amounts and synthesized by a method of wet chemical. In addition, the density functional theory (DFT) was used to model all of these samples. According to theoretical results, the bandgap energy declined continuously from 4.6297 to 4.4034eV. The linear absorption coefficient increased with increasing amounts of Sm in all samples, while this parameter decreased with increasing photon energy. There was a reduction in both the lattice parameter a and the volume of the unit cell, but there was also an increase in the lattice parameter c and theoretical density. Accordingly, the experiment's results were as follows:HAp phase (above 98% for all of the samples) and beta-tricalcium phosphate beta - TCP were both confirmed as the major phase and minor phase, respectively, by X-ray diffraction (XRD), FT-Raman spectroscopy and the Fourier transform infrared (FTIR) measurements. The addition of Sm increased in the beta - TCP phase from 0.62 to 0.86%. Same as theoretical results, it was also found that density was increasing and the volume of the unit cell decreased. An increase in anisotropic energy density and a decrease in crystallinity were discovered. The values are calculated based on the molar ratio, which was discovered to be close to those for stoichiometric HAp in all samples (1.67). Based on the results of the thermal study, all samples were confirmed to be thermally stable. Sm content was discovered to have an effect on cell viability.
  • Küçük Resim Yok
    Öğe
    Structural, magnetic, thermal, biocompatibility, and electronic properties of lanthanum doped-magnesium hydroxyapatite
    (Elsevier Sci Ltd, 2025) Mahmood, Bahroz Kareem; Kareem, Rebaz Obaid; Bulut, Niyazi; Ates, Tankut; Keser, Serhat; Kaygili, Omer; Kurucay, Ali
    This study presents the preliminary experimental and theoretical results on Mg/La co-substituted in hydroxyapatite (HAp) structure. Four Mg-based HAps were synthesized with La doping by keeping the Mg concentration constant at 0.45 at.%, while the La content was varied from 0.45 to 1.80 at.% in 0.45 at.% increments by a wet chemical method. Experimentally, the major phase for all samples was HAp and the minor phase was beta-TCP. The presence of La as a dopant for the HAp structure was found to affect the lattice parameters. The values of lattice parameters and unit cell volume were observed to increase gradually. The crystallinity percentage ranged from 85 % to 89 %. Analysis using the Scherrer and Williamson-Hall approaches revealed that the crystallite size values of the samples were in the range of 22-29 nm and 23-33 nm respectively. In addition, the values of lattice stress, strain and anisotropic energy density were influenced by the concentration of La. The magnetic saturation decreased from 0.0439 to 0.0383 emu/g with an increase in the amount of La. All samples showed biocompatible properties. A slight change in morphology was also observed. The EDX results showed that the presence of La at different levels resulted in calcium deficiency. Thermogravimetric analysis and differential thermal analysis, carried out over a temperature range of 25-850 degrees C, showed that each sample had thermal stability, with no exothermic or endothermic peaks detected. Theoretical results derived from Density Functional Theory (DFT) calculations showed that the band gap values decreased steadily from 4.578 to 4.438 eV.
  • Küçük Resim Yok
    Öğe
    The effects of Zn and Yb co-dopants on the electronic, radiation shielding, structural, thermal and spectroscopic properties of hydroxyapatite
    (Elsevier, 2024) Ayhan, Yasemin Merve; Ates, Tankut; Seckin, Turgay; Ozcan, Imren; Bulut, Niyazi; Kurucay, Ali; Kaygili, Omer
    This work presents a comprehensive investigation of the electronic properties of hydroxyapatite (HA) doped with zinc (Zn) and ytterbium (Yb). Four different compositions, namely 0.33Zn-0.33Yb-HA, 0.33Zn-0.66Yb-HA, 0.66Zn-0.33Yb-HA, and 0.66Zn-0.66Yb-HA, were studied using Density of States (DOS) and band structure calculations. The computed band gap values for each composition were determined to be 4.3097 eV, 4.1324 eV, 4.2527 eV, and 4.2088 eV, respectively. The observed decrease in the band gap energy from 0.33Zn-0.33Yb-HA to 0.66Zn-0.66Yb-HA signifies a significant impact of the dopant composition on the electronic properties of the material. Furthermore, the inclusion of ytterbium in the HA matrix resulted in the formation of a distinct band and peak in the density of states. This indicates the emergence of specific energy levels associated with Yb, suggesting a distinct influence on the electronic structure of the material. These findings provide valuable insights into the tunability of the electronic properties of HA through controlled doping with Zn and Yb. Such knowledge is crucial for tailoring materials with desired electronic characteristics, thus holding promise for various applications in electronic devices and biocompatible coatings. The as-modeled structures were synthesized via a wet chemical route. Fourier transform infrared (FTIR), Raman, and X-ray diffraction (XRD) analyses verified the formation of the HA structure for each sample. Differential thermal analysis (DTA) results showed that all the as-prepared samples were thermally stable. The negligible mass losses were detected for all the samples in the thermogravimetric analysis (TGA) measurements. The addition of both co-dopants affected crystal structure related parameters and decreased the crystallinity and cell viability.
  • Küçük Resim Yok
    Öğe
    The experimental and theoretical investigation of Sm/Mg co-doped hydroxyapatites
    (Elsevier, 2022) Hssain, Ala Hamd; Bulut, Niyazi; Ates, Tankut; Koytepe, Suleyman; Kurucay, Ali; Kebiroglu, Hanifi; Kaygili, Omer
    This study presents an extensive experimental and theoretical analysis of Mg -doped hydroxyapatite (HAp) samples with additional Sm doping at varying amounts. A wet chemical method was used to synthesize Mg-containing HAps at a constant amount of 0.133 at. %, and in addition the second dopant of Sm was utilized at varying amounts of 0.133, 0.266, 0.399, 0.532, and 0.665 at. %. All of these samples were investigated experimentally and theoretically by using the X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), in-vitro cell viability tests, and density functional theory (DFT) calculations. The bandgap energy was found to have reduced from 4.6115 eV to 4.3870 eV. The linear attenuation (or absorption) coefficient increased as the amount of Sm in the sample increased, and this parameter decreased as the photon energy increased for all samples. Both the lattice parameter and the theoretical density increased, whereas the unit cell volume and the lattice parameters declined. The XRD and FTIR results revealed that the HAp phase (over 98 percent for all samples) was a major phase formed, while the beta -TCP phase (beta-tricalcium phosphate) was a minor phase. The beta-TCP phase increased from 0.91 to 1.57 percent with an increasing amount of Sm. The volume of the unit cell trended in the same direction as predicted by the obtained results theoretically. Increased anisotropic energy density and a decrease in crystallinity have been observed. All samples were found to be thermally stable. Due to the presence of Sm content, cell viability was observed to be affected.