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Access type: UnknownAuthor: search.filters.author.Chaemlek, O.

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    Eu-Doped Gd2MoB2O9 Phosphors for Latent Fingerprints Detection
    (2022-01-01)
    Chamchoi, N.
    ;
    Sangwaranatee, N.
    ;
    Rajaramakrishna, R.
    ;
    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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    White Emission from Dy3+ Doped in ZnO–CaO–B2O3 for WLEDs Material Application
    (2022-01-01)
    Chaemlek, O.
    ;
    Kiwsakunkran, N.
    ;
    Boonpa, W.
    ;
    Wantana, N.
    ;
    Sareein, T.
    The Dy<sup>3+</sup> ions doped CaO-ZnO-B<inf>2</inf>O<inf>3</inf> glasses were synthesis by the melt quenching technique with various Dy<inf>2</inf>O<inf>3</inf> concentrations to investigation physical and optical properties. The results showed that the density and the molar volume trend to be increased along with increased Dy<sup>3+</sup> concentration. The absorption spectra showed characteristic absorption peaks in the visible and near infrared regions. Judd–Ofelt (JO) intensity parameters have been obtained from the optical absorption spectra. The emission spectra of the glasses are illustrated the highest emission intensity at 574 nm wavelength, which corresponding to Dy<sup>3+</sup> transition <sup>4</sup>F<inf>9/2</inf>→<sup>6</sup>H<inf>13/2</inf> level. The decay time value decreased as the concentration of Dy<inf>2</inf>O<inf>3</inf> increased. The CIE 1931 chromaticity investigation showed that Dy<sup>3+</sup> doped glasses emitted light with white color.