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  • Assoc. Prof. Dr. Ayen YILMAZDepartment of Chemistry Middle East Technical UniversityAnkara, TURKEY

    Prof. Dr. Glhan ZBAYOLUDean Faculty of Engineering Atlm University Ankara, Turkey

    RAD, 24-27 April 2012

  • OBJECTIVESTo synthesize metal doped Li2B4O7 to be used in TL dosimetry by using different synthesis methods.

    high temperature solid state synthesis solution assisted synthesis doping with Cu and Mn Co-doping with Ag and In together with Cu, of Ag, P and Mg together with Mn

    To determine the thermoluminescence response.

  • THERMOLUMINESCENCEHEATINGLIGHT EMISSIONRADATON EXPOSURE AND RESULTANT RADATON STORAGE

  • LITHIUM TETRABORATESYNTHESIS

    Powder: by heating hydrated precursors by wet reaction by solid state reactionsPellet: ease in lab work, final product is fragile

    Glass: cautious control of temperature (up to 1150oC) rapid cooling employed

    Crystal: require complicated systems, seed crystal

  • LITHIUM TETRABORATETL RESPONSEGlow Curve: Generally around 200 O C

  • MATERIALS AND METHODS2- METHODS

    Li2CO3 + 4H3BO3 Li2B4O7 + CO2 +6 H2O

  • MATERIALS AND METHODSHigh Temperature Solid State Synthesis

  • MATERIALS AND METHODSWater / Solution Assisted Synthesis

  • MATERIALS AND METHODSHigh Temperature Solid State Doping

    Applied to high temp. solid state synthesis product only 0.1-1.0% Cu, 0.1-10% Mn dopedHeating 25-750oC by 400oC per hr Retention2+1 hr with intermittent mixing

  • MATERIALS AND METHODSSolution Assisted Doping

    For water/solution assisted synthesis product 0.1-1% Cu

    For high temp solid state synthesis product 0.1% Cu and 1.0 % Mn best results Heating 150oC - 3 hrs, 700oC - 2 hrs

  • MATERIALS AND METHODSDopant amounts for double doping experiments

    LBO Weight (g)Cu %Ag %Cu %In %10.10.010.10.0110.10.020.10.0210.10.030.10.0310.10.040.10.0410.10.050.10.0510.30.010.30.0110.30.020.30.0210.30.030.30.0310.30.040.30.0410.30.050.30.05

  • MATERIALS AND METHODSDopant amounts for triple doping experiments

    LBO Weight (g)Cu %Ag %In %10.10.040.0110.10.040.0310.10.040.0510.10.050.0110.10.050.0310.10.050.0510.30.040.0110.30.040.0310.30.040.0510.30.050.0110.30.050.0310.30.050.05

  • RESULTS AND DISCUSSION-xrd-tlX RAY DIFFRACTION high temperature solid state synthesisa) Undoped lithium tetraborate produced by high temperature solid state synthesis b) Lithium tetraborate doped by solid state doping method c) Lithium tetraborate doped by solution assisted doping method.

  • RESULTS AND DISCUSSION-xrd-tlUndoped lithium tetraborate produced by water assisted method b)Lithium tetraborate solution assisted doping

  • THERMOLUMINESCENCE ANALYSESH.T. Solid State Synthesized

    Cu doped by H.T. Solid State

    Very low intensity around 200oCVery complicated glow curve , no noticable trend

  • Water/Soln. Assisted Synthesized

    Cu doped by Solution Assisted Technique

    Higher intensity around 100oC

    Around 200oCBest result:0.1%Cu

  • H.T. Solid State Synthesized

    Cu doped by Solution Assisted Technique

    Lower intensity around 100oC

    Main peak around 200oCBest result: 0.1%Cu

  • Glow patterns for the samples produced by solid state synthesis method and (0.1-1 % Cu) doped by solution assisted method.

  • Glow patterns for 0.1% Cu with varying amounts of Ag (0.01-0.05)Glow patterns for 0.3% Cu with varying amounts of Ag (0.01-0.05)with 0.1%Cu, 0.04% Ag coactivator gave the highest TL response.

  • Glow patterns for 0.1% and 0.3% Cu with varying amounts of In (0.01-0.05)

  • Glow patterns for 0.1% and 0.3% Cu-0.04%Ag with varying amounts of In (0.01-0.05)with 0.1%Cu, 0.04% Ag coactivator gave the highest TL response.

  • XRD patterns of solution assisted synthesized undoped LTB (a), high temperature solid synthesized undoped LTB (b), solution assisted synthesized 1 wt % Mn doped LTB (c), and high temperature solid synthesized 1 wt % Mn doped LTB Mn doping:

  • LTB synthesized with solution assisted method and solution assisted dopedLTB synthesized with solution assisted method and high temperature solid state doped

  • LTB synthesized with high temperature solid state synthesis method and solution assisted doped LTB synthesized with high temperature solid state synthesis method and high temperature solid state doped

  • Thermoluminescence measurements of LTB synthesized with high temperature solid state synthesis method and high temperature solid state doped with 0.5 wt % Ag and varying Mn content in the range of 0.1 - 1 wt %.

  • Thermoluminescence measurements of LTB synthesized with high temperature solid state synthesis method and high temperature solid state doped with 0.5 wt % P and varying Mn content in the range of 0.1 - 1 wt %.

  • Thermoluminescence measurements of LTB synthesized with high temperature solid state synthesis method and high temperature solid state doped with 0.5 wt % Mg and varying Mn content in the range of 0.1 - 1 wt %.

  • SEM images of solution assisted synthesized 1 wt % Mn solution assisted doped LTB (A), solution assisted synthesized 1 wt % Mn high temperature solid doped LTB (B), high temperature solid synthesized 1 wt % Mn solution assisted doped LTB (C), and high temperature solid synthesized 1 wt % Mn high temperature solid doped LTB (D).

  • TEM Micrograph taken from high temperature solid synthesized 1 wt % Mn high temperature solid doped LTB (A) and solution assisted synthesized 1 wt % Mn high temperature solid doped LTB (B).

  • CONCLUSIONSThe radii of Ag+ is larger than Li+ radius and LTB lattice will be destroyed, and therefore TL peaks are shifted.

    Phosphorus co-doping increased the peak intensities of glow curves because when P is doped into LTB, PO43- can replace the BO4 units, the radius of P is not too larger than boron atom, no destruction in LTB lattice would be expected.

    Electronegativity of P atom is higher than that of B atom, so impurity of P can produce electron traps in LTB crystals to enhance TL sensitivity.

    Mg2+ has approximately same ionic radii with Li+ ions however, the high charge on Mg create great valance difference to destroy the LTB lattice.

    High temperature solid state synthesis method is the way to combine highly ordered crystalline nanoparticles of the same phase because this method has diffusion control step of reactants. This step increases the time duration during crystallization.In order to obtain high intensity glow peak the sample need to be the combinations of nano sized crystallites. Having bigger single crystals reduces the glow peak intensity of sample. Preparing lithium tetraborate by solution assisted synthesis method helps the formation of bigger single crystals.

  • AcknowledgementsProf. Dr. Necmeddin Yazici, Dept. of Eng. Physics, University of Gaziantep,National BORON Research Institute for financial supportReferences: E. Pekpak, A. Yilmaz, G. Ozbayoglu, The Effect of Synthesis and Doping Procedures on Thermoluminescent Response of Lithium Tetraborate Journal of Alloys and Compounds, 509 (2011) 24662472.

    2. M. Kayhan, A. Yilmaz, Effects of Synthesis, Doping Methods and Metal Content on Thermoluminescence Glow Curves of Lithium TetraborateJournal of Alloys and Compounds, 509 (2011) 7818-7825.Thank you very much for your attention!

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