High temperature photoluminescence dependence and energy migration of Tb3+-Incorporated K3Y(BO2)6 phosphors

Abstract

(BO2)6 (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.