High temperature photoluminescence dependence and energy migration of Tb 3+ -Incorporated K 3 Y(BO 2 ) 6 phosphors

This study investigates the structural and photoluminescence (PL) characteristics of Tb -incorporated K Y(BO ) (KYBO) phosphors synthesized via a microwave-assisted sol-gel technique. X-ray diffraction (XRD) and Rietveld refinement confirmed the formation of a pure hexagonal phase, with lattice expansion due to Tb³⁺ doping. PL studies revealed strong green emissions centered at 541 nm, attributed to the ⁵D₄ → ⁷F₅ transitions of Tb³⁺ ions, with the highest intensity observed at 5 wt% Tb³⁺. A decrease in emission was observed at higher concentrations due to concentration quenching. Temperature-dependent PL measurements revealed reverse thermal quenching enhancing PL intensity. Chromaticity analysis based on CIE 1931 coordinates showed stable green emission across all concentrations, with a maximum color purity of 89.74% observed for the KYBO:3 wt% Tb³⁺ sample. The results, along with reverse thermal quenching behavior observed between 470K and 550K, suggest that these phosphors exhibit excellent potential for lighting and display technologies.