Yazar "Cetin, Ahmet" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Effects of CdS quantum dot in polymer nanocomposites: In terms of luminescence, optic, and thermal results
    (Pergamon-Elsevier Science Ltd, 2019) Keskin, Ilker Cetin; Türemiş, Murat; Kati, Mehmet Ismail; Kibar, Rana; Cetin, Ahmet
    CdS quantum dots (QDs) which have unique luminescence efficiency were synthesized by two-phase method using oleic acid (OA) as a surfactant. The nanocomposites have been obtained by blended CdS quantum dots with low-density polyethylene (LDPE) in different ratios. Primarily, radioluminescence (RL) properties were investigated as well as their structural (FT-IR, XRD), morphological (TEM, SEM), thermal (TG-DTA) and absorption (UV-Vis) properties of these nanocomposites. The RL peaks of OA-capped CdS QD were observed at 456 nm and 655 nm. As a consequence of the nanocomposites being doped with powder CdS QD, a significant blue shift was observed in the absorption bands. The optical band gap of CdS was calculated as- 2.3 eV. The nanocomposites blended with CdS QD, this value increased to- 2.7 eV. It has also been observed that nano particles cause nanocomposites to have lower melting temperatures.
  • Küçük Resim Yok
    Öğe
    X-ray irradiated thermo- and radioluminescence, structural and thermal characterization of septarian (powder&bulk) from Madagascar
    (Elsevier, 2018) Keskin, Ilker Cetin; Kati, Mehmet Ismail; Türemiş, Murat; Gultekin, Serdar; Ustun, Siileyman; Cetin, Ahmet
    The luminescence properties of septarian have been investigated for the first time in this study, which has been the subject of many studies in both geological and geophysical fields. This sediment with a calcium carbonate structure exhibited high luminescence properties with X-ray excitation. The radioluminescence (RL) and thermoluminescence (TL) properties were investigated as well as their structural (FT-IR, XRD), morphological (SEM), thermal (TG-DTA) and absorption (UV-Vis-NIR) properties of this sediment. The broad RL peak of septarian was observed at 640 nm. There was a significant increase in the RL intensities of the sifted samples compared with the bulk sample. The TL glow curves of septarian irradiated with X-rays exhibited intense main TL glow peak having the maximum temperatures at 116 degrees C and about 390 degrees C with a heating rate of 2 degrees C/s. Also; the TL kinetic parameters were reported; activation energy (E), frequency factor (s) and the order of kinetics (b) of the first peak have been determined in detail by using peak shape (PS) and Computerized Glow Curve Deconvolution (CGCD) methods. SEM and EDS analysis were performed for the two different layers of septarian. The light colored side with the amorphous structure of the sample has more impurities (such as Fe, Al, Zr, K) than the crystallized and darker side.