Structural, thermal, and optical properties of Dy3+ /K+ Co-Doped SmCa4O (BO3)3 phosphors synthesized by Sol-Gel method

Abstract

This study investigates the structural, thermal, and optical properties of Dy3+ /K+ co-doped SmCa4O(BO3) 3 (SmCOB) phosphors synthesized using a sol-gel method. X-ray diffraction (XRD) analysis confirmed the high crystallinity and phase purity of the SmCOB lattice. Rietveld refinement further detailed slight lattice parameter modifications induced by Dy3+ and K+ doping. Fourier-transform infrared (FTIR) spectroscopy identified characteristic vibrational modes of the SmCOB matrix, including symmetric and asymmetric B- O stretching vibrations. These modes remained largely unaltered after doping, indicating the structural stability of the host lattice. Photoluminescence (PL) studies excited at 369 nm identified Dy3+ emission peaks at 468 nm (blue), 574 nm (yellow), and a dominant 657 nm (4 F9/2 -> 6 H11/2). Co-doping with K+ increased the PL intensity by 26 %, attributed to charge compensation, reducing non-radiative losses and optimizing the local crystal field around Dy3+ ions. Luminescence decay analysis revealed that the Dy3+-doped sample exhibited a longer lifetime component (456.6 ls) compared to the undoped sample. Furthermore, K+ co-doping led to a significant increase in the average lifetime (752.8 ls), suggesting a further reduction in non-radiative decay pathways. Temperature-dependent PL analysis demonstrated excellent therm al resistance, with a high activation energy (Ea = 0.258 eV) for K+ co-doped samples, highlighting their suitability for high-power lighting applications. Chromaticity measurements positioned the phosphors in the cold white light region, demonstrating their potential for energy-efficient lighting and advanced display technologies. (c) 2025 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights are reserved, including those for text and data mining, AI training, and similar technologies.