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    Fabrication luminescence and radiation shielding properties of Gd2O3–La2O3–ZnO–B2O3–Sm2O3 glasses
    (2023-01-01)
    Kaewjaeng, S.
    ;
    Kothan, S.
    ;
    Wantana, N.
    ;
    Kim, H. J.
    ;
    Rajaramakrishna, R.
    The purpose of developing high transparency radiation shielding materials and luminescence materials with stoichiometric ratio of xGd<inf>2</inf>O<inf>3</inf>:10La<inf>2</inf>O<inf>3</inf>:10ZnO:(79-x) B<inf>2</inf>O<inf>3</inf>: 1Sm<inf>2</inf>O<inf>3</inf> where x = 0, 5, 10, 15, and 20 mol% using melt quenching technique. The physio-optical properties such as molar volume, density, concentration of rare-earth ions, polaron radius, inter-ionic radius, optical basicity, average distance between rare-earth ions, and optical packing density of the present glasses has been evaluated. The glass samples obtained show high density which is vital factor for radiation shielding. The absorption spectra show significant of bands Sm<sup>3+</sup> ions. The FTIR results of Gd-La-Zn-B-Sm (Gd-1Sm) glass samples show signature borate BO<inf>3</inf> and BO<inf>4</inf> vibrational units in Gd-1Sm glass samples. The μ, μ<inf>m</inf>, HVL, TVL, and MFP were evaluated and showed that the values decrease with increasing X-ray energy whereas increase with an increase in Gd<inf>2</inf>O<inf>3</inf> content suggesting their potential use in X-ray diagnosis regions. The HVL value was compared with commercial windows, concrete, Serpentine and X-ray windows and found that the glasses doped with 10 mol%, 15mol%, and 20 mol% Gd<inf>2</inf>O<inf>3</inf> content showed better results than X-Ray windows at 10 kVp. The emission and excitation spectra of glass samples were studied and emission spectra show orange emission bands. The experimental lifetime analysis shows that the glass samples show decreasing trend from 1.161 to 1.128 ms with an increase in Gd<sup>3+</sup> ions exhibiting single exponential nature.
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    Eu-Doped Gd2MoB2O9 Phosphors for Latent Fingerprints Detection
    (2022-01-01)
    Chamchoi, N.
    ;
    Sangwaranatee, N.
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    Rajaramakrishna, R.
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    Kim, H. J.
    ;
    Chaemlek, O.
    The luminescent powders from rare-earth ions doped oxides have been successfully used for latent fingerprint detection due to high efficiency, high contrast and low background interface. The Gd<inf>2</inf>MoB<inf>2</inf>O<inf>9</inf>:Eu<sup>3+</sup> phosphors with varying compositions of Eu<sup>3+</sup>ions were synthesized by solid state reaction method. These phosphors were investigated by X-ray diffraction (XRD), diffuse reflectance spectroscopy, photoluminescence (PL), and decay curves studies. Multiphoton relaxation decay rate and coupling strength was evaluated using phonon side band spectrum showing 0.4 mol% doped samples show less non radiative decay rate. The 0.40 mol% of Eu<sup>3+</sup> ion concentration doped in the Gd<inf>2</inf>MoB<inf>2</inf>O<inf>9</inf> host lattice show highest photoluminescence emission intensity at 613 nm, in orange red region, monitored at 394 nm excitation. The Gd<inf>2</inf>MoB<inf>2</inf>O<inf>9</inf>:Eu<sup>3+</sup> phosphors samples were optimized to 900 °C sintering temperature and optimum milling time at 3 min in the present work. The latent fingerprints detection that developed from Gd<inf>2</inf>MoB<inf>2</inf>O<inf>9</inf>:Eu<sup>3+</sup> phosphors in this work exhibited clearly ridge characteristics under UV illumination. The results revealed thatGd<inf>2</inf>MoB<inf>2</inf>O<inf>9</inf>:Eu<sup>3+</sup> phosphors are potential practical forensic science applications.
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    Effect of Gd2O3 on the radiation shielding, physical, optical and luminescence behaviors of Gd2O3–La2O3–ZnO–B2O3–Dy2O3 glasses
    (2021-08-01)
    Kaewjaeng, S.
    ;
    Wantana, N.
    ;
    Kothan, S.
    ;
    Rajaramakrishna, R.
    ;
    Kim, H. J.
    The present work focuses on lead-free glasses, their shielding behavior, and other optical studies. The glass composition with xGd<inf>2</inf>O<inf>3</inf>+10La<inf>2</inf>O<inf>3</inf>+10ZnO+(79-x) B<inf>2</inf>O<inf>3</inf>+1Dy<inf>2</inf>O<inf>3</inf>, x = 0, 5, 10, 15, 20 mol% were prepared to the characterization on physical, absorption spectra, photo-, radioluminescence, and radiation shielding properties. In the experimental results, the density of Gd-1Dy glass samples increases with the increase of Gd<sup>3+</sup> ions concentrations. The ten-strong peak in the 5Gd-1Dy glass of absorption spectra in UV–Vis–NIR regions. The white photoluminescence spectra base of Gd-1Dy glass samples can be generated under excitation at 351 nm makes the strongest emission of Dy<sup>3+</sup> ions and excitation through energy transfer from Gd<sup>3+</sup> in Gd-1Dy glass samples with 275 and 351 nm. This strong white emission of Dy<sup>3+</sup> ions also strong in x-ray luminescence and performs the integral scintillation efficiency of 33% when compared with BGO crystal. The radiation shielding properties in the diagnostic medicine energies region are correlated, the values of glass samples better than commercial windows, bricks, and concrete. The HVL values of glass sample at 15 and 20 mol% of Gd<inf>2</inf>O<inf>3</inf> has been found better than X-ray windows. The corollaries of Gd-1Dy glass samples can be a candidate for radiation detector and lead-free radiation shielding materials in future.
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    White Emission from Li2O-BaO-Bi2O3-P2O5 Glass Doped with Dy3+ for Optical Condensed Material Applications
    (2021-01-01)
    Tongdang, J.
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    Chanthima, N.
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    Kiwsakunkarn, N.
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    Tariwong, Y.
    ;
    Rajaramakrishna, R.
    Dy<sup>3+</sup>-doped lithium barium bismuth phosphate glasses were synthesized by the melt-quenching. The structural characteristics of the synthesized glasses were investigated by Fourier transform infrared (FTIR) spectroscopy. Symmetric and asymmetric vibrations of phosphorous oxygen groups were prominent bands in the FTIR spectra. Judd–Ofelt theory have been evaluated by the intensities of absorption bands in order to calculate oscillator strength (f). Luminescence intensity increases with increase in BaO content due to substitution of Ba<sup>2+</sup> replacing Bi<sup>3+</sup> which lead more void spaces providing enough space for Dy<sup>3+</sup> ions to fit in. The branching ratio β parameter was distinguished to be maximum for the emission transition of <sup>4</sup>F<inf>9/2</inf> → <sup>6</sup>H<inf>13/2</inf> with the values of 0.59. LBBPDy glasses reveal an ideal warm white region when observed in CIE diagram. Our investigation reveals that the synthesized glasses may be utilized as a solid-state lighting material in various technological and industrial applications.