Browsing by Author "Karsu E.C."

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    Kinetic characterization of MgB4O7: Dy,Na thermoluminescent phosphor
    (Institute of Physics Publishing, 2006) Karsu E.C.; Gökçe M.; Ege A.; Karali T.; Can N.; Prokic M.
    Dosimeters of MgB4O7 doped with Dy and Na have many valuable features such as high sensitivity, tissue equivalence, low fading, non-requirement of annealing and insensitivity to light. Thermoluminescence studies of Dy and Na doped MgB4O7 samples showed that a glow emission peaked at about 195 °C. In this study, the trapping parameters associated with the main dosimetric peak, namely at 195 °C, of Dy and Na doped MgB4O7 are investigated. Isothermal luminescence decay, glow curve shape, initial rise (linear regression) and Tm - Tstop methods were used. We report the results on the kinetic behaviour and activation energy determination of the peak occurring at 195 °C with a moderate heating rate of 2 °C s-1. The average activation energies obtained by the isothermal luminescence decay method, glow curve shape method and initial rise method are calculated to be 1.03 eV, 0.95 eV and 0.89 eV, respectively. The methods mentioned above indicate that the dosimetric peak may consist of one or more second-order components. The frequency factors obtained by the three methods are 3.5 × 1010 s-1, 1.6 × 109 s-1 and 3.4 × 108 s-1, respectively. Results obtained using all these methods are compared and discussed. © 2006 IOP Publishing Ltd.
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    Luminescence study of some yttrium tantalate-based phosphors
    (2011) Karsu E.C.; Popovici E.J.; Ege A.; Morar M.; Indrea E.; Karali T.; Can N.
    Yttrium tantalate (YTaO4), yttrium niobium-tantalate (YTaNbO4), yttrium niobate (YNbO4), europium and terbium activated yttrium tantalate (YTaO4:Eu, YTaO4:Tb) and europium activated yttrium niobate (YNbO4:Eu) phosphors were prepared by solid-state reaction, from a homogeneous mixture consisting of Y 2O3, Eu2O3, Tb4O 7, Ta2O5, Nb2O5 and Na2SO4 as flux. Photoluminescence (PL), thermally stimulated luminescence (TSL), X-ray diffraction (XRD) and scanning electron microscopy (SEM) of yttrium tantalate based phosphors are reported. In the present study TSL characteristics of these phosphors were first investigated and reported after exposure to beta, UV (311 nm) and X-ray radiations. © 2010 Elsevier B.V. All rights reserved.
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    Spectroscopy, thermoluminescence and afterglow studies of CaLa4(SiO4)3O:Ln (Ln=Ce, Nd, Eu, Tb, Dy)
    (Elsevier B.V., 2015) Dobrowolska A.; Karsu E.C.; Bos A.J.J.; Dorenbos P.
    The spectroscopic characterization down to 10 K was performed for undoped and Ln doped CaLa4(SiO4)3O (Ln=Eu3+, Eu2+, Ce3+, Dy3+, Tb3+). Based on the experimental and literature data the scheme was constructed showing the vacuum referred binding energy (VRBE) of electrons in lanthanide states and band states in CaLa4(SiO4)3O. This scheme predicts that co-doping with Eu2+ and Ln3+ (Ln=Dy, Nd) will induce afterglow. Thermoluminescence and afterglow were indeed measured and compared with a commercial SrAl2O4:Eu, Dy afterglow phosphor. © 2015 Elsevier B.V. All rights reserved.