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    Insight into the Photoluminescence of Ba2Cd(BO3)2: RE3+ (RE = Dy, Tb) Phosphors
    (Springer/Plenum Publishers, 2025) Toreli, S. B.; Kafadar, V. E.; Emen, F. M.; Ozturk, E.; Altinkaya, R.
    Dy3+ and Tb3+ ions doped Ba2Cd(BO3)2 phosphors with varying concentrations (2, 3, 4, 5, 6 mol%) were produced via the solid-state synthesis method in air. The as-synthesized phosphors were characterized. The photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Ba2Cd(BO3)2 phosphors doped with 2, 3, 4, 5, and 6 mol% Dy3+ ions reveal four distinct emission bands in the blue, yellow, and red regions, with the 575 nm emission band (4F9/2 -> 6H13/2, electric dipole transition) exhibiting a notably higher intensity than the 481 nm band (4F9/2 -> 6H15/2, magnetic dipole transition). The optimal Dy3+ doping concentration was identified as 5 mol%, beyond which concentration quenching effects became apparent. Additionally, excitation and emission spectra of Ba2Cd(BO3)2 phosphors doped with 2, 3, 4, 5, and 6 mol% Tb3+ ions demonstrate efficient energy absorption at approximately 225 nm, with characteristic emission bands observed at 415, 436, 488, 544, 586, and 621 nm, corresponding to the 5D3 -> 7F5, 5D3 -> 7F4, 5D4 -> 7F6, 5D4 -> 7F5, 5D4 -> 7F4, and 5D4 -> 7F3 transitions, respectively. The ideal concentrations for Dy3+ (5 mol%) and Tb3+ (6 mol%) in Ba2Cd(BO3)2 are identified at x = 0.3717, y = 0.4064, and x = 0.2902, y = 0.5344, respectively, as per the Commission Internationale de l'Eclairage (CIE) color spectrum, positioning Dy3+-doped phosphors within the yellow spectrum and Tb3+-doped phosphors within the green spectrum. These phosphors exhibit vibrant yellow and green luminescence, demonstrating their suitability as candidates for applications in these hues. They can be employed when stimulated by near-UV, UV, and blue laser diodes for WLEDs.
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    Öğe
    Synthesis and Photoluminescence Properties of Eu3+-Activated Ba2Cd(BO3)2 Red-Emitting Phosphors for Near-Ultraviolet Excited White Light-Emitting Diodes
    (Wiley, 2025) Toreli, S. B.; Kafadar, V. E.; Emen, F. M.; Ozturk, E.; Altinkaya, R.
    A new class of rare-earth doped borate phosphors, Ba2Cd(BO3)(2): xEu(3+) (x = 2, 3, 4, 5, and 6 mol%), was synthesized using the high-temperature solid-state reaction technique in air. X-ray diffraction (XRD) confirmed the phase formation of Ba2Cd(BO3)(2), while Fourier transform infrared spectroscopy (FT-IR) revealed the presence of trigonal [BO3] units. The surface morphology was studied using field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) identified the elements. Photoluminescence (PL) analysis showed that the phosphors emitted at 592, 613, 652, and 701 nm, corresponding to the D-5(0) -> F-7(1), D-5(0) -> F-7(2), D-5(0) -> F-7(3), and D-5(0) -> F-7(4) transition of Eu3+ ions, respectively. The 613 nm red emission, from the D-5(0) -> F-7(2) transition, was strongest for the 6 mol% Eu3+ sample. The emission intensity increased with Eu3+ concentration, peaking at 6 mol%. CIE chromaticity, correlated color temperature (CCT), and color purity calculations showed acceptable color coordinates (0.6426 and 0.3548), a low CCT value (2355 K), and high purity (91.34%), making the 6 mol% Eu3+-doped phosphor ideal for red light in white light-emitting diodes (WLEDs).