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Öğe Ce/Sm co-doped hydroxyapatites: synthesis, characterization, and band structure calculation(Springer, 2020) Kaygılı, Ömer; Vural, Gülay; Keser, Serhat; Yahia, İ.S.; Bulut, Niyazi; Ateş, Tankut; Köytepe, Süleyman; Temüz, Mehmet Mürşit; Ercan, Filiz; İnce, TuranIn this paper, Ce/Sm co-doped hydroxyapatites (HAps) were synthesized by a wet chemical route. The amount of Ce was kept at constant at the value of at.% 0.4, and the second dopant of Sm was used at different amounts of at.% 0, 0.6, 1.2, and 1.8, respectively. The effects of these co-dopants on the crystal structure, morphology, and thermal properties of HAp were determined experimentally using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), and thermogravimetric analysis (TGA). Furthermore, the band structure of the prepared samples was modeled theoretically using the quantum calculations of the density of states and band structure. A gradual increase from 26.56 to 36.23 nm in the crystallite size was observed. Although the amounts of the co-dopants of Ce and Sm did not affect the thermal stability and microstructure of HAp, its crystal structure-related parameters were affected by the amount of these co-additives. The partial substitution of both co-dopants was detected. The 0.4Ce-1.2Sm-HAp sample may be considered as the best crystal structure with a steady-state. It was seen that the band structure and density of states were also affected by these co-dopants. The bandgap value decreased gradually from 4.6078 to 4.0477 eV due to these dopants.Öğe Investigation of the effects of Ni-doping on the structural and thermal properties of ZnAl2O4 spinels prepared by wet chemical method(Springer, 2021) Ercan, Filiz; Ateş, Tankut; Kaygılı, Ömer; Bulut, Niyazi; Köytepe, Süleyman; Alahmari, Fatimah; Ercan, İsmail; Hssain, Ala Hamdn this study, a more detailed characterization of the un-doped and Ni-doped ZnAl2O4 spinel structures prepared via a facile wet chemical route was carried out. Significant effects of the additive of Ni on the ZnAl2O4 structure were observed. For all the samples, the ZnO phase was detected as the second phase, and the third phase of NiO was observed for two samples having the highest Ni content. X-ray diffraction (XRD) results showed that the crystallinity percent, lattice parameter, and volume of the unit cell decreased continuously with adding of Ni. Fourier transform infrared (FTIR) spectra verify the formation of the ZnAl2O4 structure for all the samples. The thermal behaviors, including the recrystallization temperature and mass losses, of the ZnAl2O4 structure, were also affected by the amount of Ni. The morphology varied with adding of Ni. These properties were not reported before.Öğe Structural, spectroscopic, dielectric, and magnetic properties of Fe/Cu co-doped hydroxyapatites prepared by a wet-chemical method(Elsevier, 2022) Ercan, İsmail; Kaygılı, Ömer; Kayed, Tarek; Bulut, Niyazi; Tombuloğlu, Hüseyin; İnce, Turan; Al Ahmari, Fatımah; Kebiroğlu, Hanifi; Ateş, Tankut; Almofleh, Atheel; Fırdolaş, Fatih; Köysal, Oğuz; Al-Suhaimi, Ebtesam Abdullah; Ghrib, Taher; Sözeri, Hüseyin; Yıldız, Mesut; Ercan, Filiz; Ateş, TankutIn this study, the effects of Cu and Fe additives on the structural, dielectric, magnetic, thermal and morphology of hydroxyapatite (HAp) samples were investigated and reported in detail for the first time. The prepared systems were also modeled and examined theoretically. It can be said that both additives affect the thermal behavior of the HAp structure. The addition of Cu affected the morphology of submicron-sized particles with spherical-like shapes with a low degree of agglomeration. Diffuse reflection data revealed that the energy band gap values decreased as Cu was added to the Fe-based HAp structure. The dielectric constant (??) had high values at low frequencies in all samples and decreased with increasing frequency. It could be concluded that Fe/Cu incorporation to hydroxyapatites enhanced its thermal, magnetic, and dielectric properties required for mimicking natural HAps to open a successful venue for medical application in the healing regeneration of bone.Öğe Theoretical and experimental characterization of Pr/Ce co-doped hydroxyapatites(Elsevier, 2021) İbrahimzade, Lala; Kaygılı, Ömer; Dündar, Serkan; Ateş, Tankut; Dorozhkin, Sergey V.; Bulut, Niyazi; Köytepe, Süleyman; Ercan, Filiz; Gürses, Canbolat; Ercan, Filiz; Hssain, Ala HamdThis study presents a more extensive report on the experimental and theoretical characterization of the Ce-doped hydroxyapatite (HAp) samples additionally doped with Pr at varying amounts. To achieve this goal, four Ce-containing (a constant amount of 0.35 at.%) HAps additionally doped with Pr at various amounts (0.35, 0.70, 1.05, and 1.40 at.%) were synthesized via a combustion method. Besides, all these samples were modeled theoretically by using a density functional theory (DFT). Theoretical results showed that the bandgap energy decreased continuously from 4.5156 to 4.3097 eV. For all samples, the linear attenuation (or absorption) coefficient increased with the increasing amount of Pr and this parameter had a decreasing trend with the increase in the photon energy. An increase in the theoretical density and the lattice parameter c and a decrease of both the lattice parameter a and the unit cell volume were found. After analyzing the experimental data, the following results were observed: X-ray diffraction (XRD) and Fourier transform infrared (FTIR) data verified the formation of HAp phase (above 94% for all the samples) as the major phase and beta-tricalcium phosphate (?-TCP) as the minor one. The amount of ?-TCP phase was found to increase from 3.4 to 5.9% with the addition of Pr. Similar to the theoretical findings, an increasing trend for the density and decreasing one for the unit cell volume were detected. Both a decrease in the crystallinity and an increase in the anisotropic energy density were found. The results of the thermal analysis supported the thermal stability of all the samples. The cell viability was found to be affected by Pr-content.
