Browsing by Subject "NASR2NB5O15"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Assessing of Photoluminescence and Thermoluminescence Properties of Dy3+ Doped White Light Emitter TTB-Lead Metatantalate Phosphor
    (SPRINGER) Ilhan, M; Keskin, IÇ; Gültekin, S
    Trivalent Dy doped TTB (tetragonal tungsten bronze) lead tantalate (PbTa2O6) phosphors were synthesized by the solid-state reaction route. Structural and spectroscopic properties have been carried out by x-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), photoluminescence (PL) and thermoluminescence (TL) analyses. XRD patterns of samples revealed the presence of TTB symmetry which continued up to 10 mol.%. SEM analysis showed the transformation of grain morphology from the shapeless-rounded to elongate. Strong PL emissions of PbTa2O6:Dy3+ phosphor were monitored at 480.5 nm and 578.5 nm. PL emission increased up to 7 mol.% and then decreased because of the concentration quenching. Decay times decreased with the increase of concentration and the end of the process (10 mol.%) fell to 355 mu m. The energy transfer efficiency (eta(ET)) energy transfer rate (W) and quantum efficiency (eta(QE)) of the whole process were found as 56.25%, 1.581 ms(-1), and 20.27%, respectively. The CIE (Commission Internationale de l'eclairage) coordinates of all phosphors have located close to the standard white light center, also the CIE coordinates (x, y) and CCT (correlated color temperature) value for 7 mol.% phosphor were found as (0.310, 0.295) and 6238 K, respectively. TL emissions of PbTa2O6:Dy3+ phosphor were monitored by four glow peaks in the range between 50 degrees C and 400 degrees C after x-ray irradiation. TL kinetic parameters were determined by the deconvolution of the 5 mol.% sample which has the highest glow curve intensity.
  • No Thumbnail Available
    Item
    Evaluation of structural behaviour, radioluminescence, Judd-Ofelt analysis and thermoluminescence kinetic parameters of Eu3+ doped TTB-type lead metaniobate phosphor
    (ELSEVIER) Ilhan, M; Keskin, IÇ
    In this study, the structural and spectroscopic properties of orthorhombic PbNb2O6 doped with different concentrations of Eu3+ were studied. Interestingly, XRD analysis of undoped PbNb2O6 showed rhombohedral phase while Eu3+ doped structures exhibited an orthorhombic phase at 1250 degrees C. This difference was also observed in the morphology and composition of grains by SEM-EDS analysis. PL and RL emissions occurred between 550 and 850 nm owing to the 4f-4f transitions of Eu3+ . The Judd-Ofelt theory was applied to the experimental data for determination of the Judd-Ofelt parameters (Omega(2), Omega(4)), radiative transition rates (A(r)) and radiative lifetimes (tau(r)). TL glow curves were monitored by the peaks of 98 and 250 degrees C while emission increased up to 6 mol%. TL emission of 6 mol% phosphor depending on X-ray irradiation dose exhibited the highest intensity for 1200 Gy and appeared new peaks. Moreover, the TL emission of phosphor showed a linear relation with X-ray irradiation. The deconvolution peaks of 1200 Gy irradiated samples were determined by the CGCD method. Kinetic data of first peak (98 degrees C) depending on the dose increase were calculated by the PS method.