Investigation of the Lumino-structural Behavior Characteristics and Technological Integration Properties of KCGBO {K7CaGd2(B5O10)3} Nanophosphor Structures Doped with Rare Earth Ions
Project no. 33037 · Status: Kapanmış · 2025
Summary
<p class="ql-align-justify">In this project, terbium (Tb3+)-activated, lithium/sodium (Li+/Na+) co-doped green-emitting nanophosphor powders based on the K7CaGd2(B5O10)3 (KCGBO) borate host were synthesized for the first time via a sol-gel assisted microwave combustion method. Samples prepared with varying Tb3+ contents (0.5-7 wt%) and alkali co-dopant levels (0.5-7 wt%) were characterized structurally, morphologically, vibrationally, and optically using XRD/Rietveld refinement, SEM-EDS, FTIR, Raman, and photoluminescence (PL) spectroscopy. XRD results confirmed that all compositions crystallize in the single-phase, non-centrosymmetric trigonal R32 space group. Under 378 nm excitation, strong green emission at ~540-544 nm (5D4→7F5) was optimized at 3 wt% Tb3+, beyond which concentration quenching (dominated by dipole-dipole interactions, Q≈5.31) was observed. Li+ and Na+ co-doping markedly enhanced the emission intensity, color purity (from ~62% to over 90%), and internal quantum efficiency (from 68.6% to 91.0%). Judd-Ofelt analysis showed that the Li+ co-doped sample exhibited the highest spontaneous emission probability (AJ) and optical gain (G). Temperature-dependent measurements demonstrated that the Li+ co-doped phosphor retained 82% of its initial intensity at 450 K (Ea≈0.52 eV), confirming superior thermal stability. The findings of this project were published by the project team in Materials Research Bulletin. Overall, the results indicate that KCGBO:Tb3+,Li+ is a promising green-emitting phosphor for near-UV-excited solid-state lighting and display applications.</p>