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    The effects of Ni-addition on the crystal structure, thermal properties and morphology of Mg-based hydroxyapatites synthesized by a wet chemical method
    (Elsevier Sci Ltd, 2018) Ince, Turan; Kaygili, Omer; Tatar, Cengiz; Bulut, Niyazi; Koytepe, Suleyman; Ates, Tankut
    Four Mg-based hydroxyapatites (HAps) doped with Ni at various amounts of 0, 0.6, 1.2 and 1.8 at% were prepared at the temperature of 870 degrees C by a wet chemical synthesis. The crystallite size, lattice parameters and crystallinity percent dramatically decreased with adding of Ni. The amount of HAp phase for all the Ni-containing samples is smaller than that of the Ni-free MgHAp. Furthermore, the lattice strain, stress and anisotropic energy density values were affected by the amount of Ni. The differential thermal analysis (DTA) measurements taken in the temperature range from 25 to 1000 degrees C showed that all the samples are thermally stable. No significant change in the morphology was observed. It was observed that the gradual introduction of Ni caused the Ca-deficiency.
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    Investigation of the structural and thermal properties of Y, Ag and Ce-assisted SiO2-Na2O-CaO-P2O5-based glasses derived by sol-gel method
    (Springer, 2017) Kaygili, Omer; Keser, Serhat; Tatar, Cengiz; Koytepe, Suleyman; Ates, Tankut
    A glass with the composition of the SiO2-Na2O-CaO-P2O5 was synthesized by sol-gel method at temperature of 900 A degrees C, and then yttrium-, silver- and cerium-containing glasses were prepared at the same conditions using this base system. The structural and thermal properties of the glass samples were investigated by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive X-ray (EDX) spectroscopy and differential thermal analysis techniques. The Ca-5(PO4)(2)(SiO4)(6) phase having the orthorhombic crystal system is detected for each sample without any secondary phase, and this phase is confirmed by the FTIR spectra. With the addition of Y, Ag and Ce to the SiO2-Na2O-CaO-P2O5 system, the variations in the average crystallite size, crystallinity percent, lattice parameters and unit cell volume are observed. A decrease in the crystallization peak temperature and the changes in the glass transition temperature are seen with the addition of Y, Ag and Ce to the base system. The addition of Y, Ag and Ce to the base glass increases significantly its density. The EDX spectra of the as-prepared samples verify the introduction of the as-mentioned elements.
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    Structural and thermal properties of Zn-containing magnesium aluminate spinels obtained by wet chemical method
    (Sciendo, 2019) Kaygili, Omer; Bulut, Niyazi; Ates, Tankut; Ercan, Ismail; Koytepe, Suleyman; Seckin, Turgay; Tatar, Cengiz
    In the present study, the dopant effect of Zn on the crystal structure, thermal properties and morphology of magnesium aluminate (MgAl2O4) spinel (MAS) structure was investigated. A pure and two Zn-containing MASs (e.g. MgAl1.93Zn0.07O4 and MgAl1.86Zn0.14O4) were synthesized for this purpose via a wet chemical method, and the as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy techniques. It was found that the crystal structure, thermal properties and morphology of the MAS system change with the increase in the amount of Zn. MgO phase formation was observed. The values of the lattice parameter, unit cell volume and crystallite size increased, and the crystallinity percentage decreased. The morphology was also affected by adding of Zn.