Yazar "Yakuphanoglu, Fahrettin" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    Electrical characterization of ZnO/NiO p-n junction prepared by the sol-gel method
    (Springer Heidelberg, 2017) Akyuzlu, A. Merih; Dagdelen, Fethi; Gultek, Ahmet; Hendi, A. A.; Yakuphanoglu, Fahrettin
    ZnO and NiO films were synthesized on fluourine-doped tin oxide (FTO) glass substrate by the sol-gel method. The surface morphology of the films was investigated by atomic force microscopy. The optical band gaps of the ZnO and NiO films were found to be 3.198 and 3.827eV, respectively. A ZnO/NiO p-n junction diode was prepared and electrical charge transport mechanism of the diode was analyzed using thermionic emission and Norde functions. The ideality factor, barrier height and series resistance of the diode were determined to be 6.46, 1.036eV and 39.1 M , respectively. The obtained results indicate that ZnO/NiO p-n junction can be used as transparent diode for optic communications.
  • Küçük Resim Yok
    Öğe
    Structural and dielectric properties of yttrium-substituted hydroxyapatites
    (Elsevier, 2015) Kaygili, Omer; Dorozhkin, Sergey V.; Ates, Tankut; Gursoy, N. Canan; Keser, Serhat; Yakuphanoglu, Fahrettin; Selcuk, A. Birkan
    Hydroxyapatite (HAp) samples doped with 0,2 and 4 at.% of yttrium (Y) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FOR) spectroscopy, scanning electron microscopy attached with energy dispersive X-ray (EDX) spectroscopy, antimicrobial activity tests and dielectric studies. The hydroxyl groups observed in FOR spectra confirmed the formation of HAp phase in the studied samples. The crystallite size, crystallinity degree and lattice parameters of the samples were changed with Y content The volume of the unit cell was gradually decreased with the addition of Y. Undoped and Y-containing HAp samples were screened to determine their in vitro antimicrobial activities against the standard strains. It was found that no samples have any antimicrobial effect. The relative dielectric permittivity and dielectric loss are affected by Y content. While the alternating current conductivity increases with increasing frequency, it decreases with increasing Y content (C) 2014 Elsevier B.V. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Structural and Dielectrical Properties of Ag- and Ba-Substituted Hydroxyapatites
    (Springer, 2014) Kaygili, Omer; Keser, Serhat; Dorozhkin, Sergey V.; Yakuphanoglu, Fahrettin; Al-Ghamdi, Ahmed A.; Kirbag, Sevda; Sertkaya, Duygu
    Ag- and Ba-doped hydroxyapatite (HAp) samples were synthesized by sol-gel method. The crystallite sizes for all the samples were found to vary from 26 to 39 nm. Neither Ag nor Ba did result in dramatic changes in the morphology of all the samples, and the Ca/P molar ratio was varied. The dielectric parameters of the samples were changed with the dopant content. The maximum and minimum values of the dielectric constant were observed for 2.0 %Ba-HAp and 0.5 %Ba-HAp samples. The alternating current conductivity indicates that all the samples exhibit the insulator behavior. The results of the biological tests revealed that Ag-containing samples have an antimicrobial activity, while no antimicrobial activity was detected for both HAp and Ba-doped HAp samples.