Enhanced luminescence and quenching mechanisms in Na plus Co-doped K7CaY2(B5O10)3:Tb3+phosphors under UV radiation

This study investigates the structural and luminescent properties UV radiation of Tb3+-doped K7CaY2(B5O10)3 (KCYBO) phosphors prepared using a microwave-assisted sol-gel method, with a focus on the impact of Na+ co- doping. Tb3+ions were effectively integrated as evidenced by X-ray diffraction (XRD) and Rietveld analysis, without disrupting the crystal structure. Photoluminescence (PL) analysis showed intense green emissions at 542 nm, which are due to the 5 D 4 -> 7 F 5 transition in Tb3+. Optimal luminescence was observed at 3 wt% Tb3+, beyond which concentration quenching effect was driven by non-radiative cross-relaxation between adjacent Tb3+ions. Na+ co-doping enhanced PL intensity by improving energy transfer and reducing non-radiative losses. CIE chromaticity coordinates demonstrated a tunable color shift towards warmer tones with increasing Na+ concentration. Thermal stability was assessed through the Arrhenius equation, with an activation energy of 0.31 eV, indicating the material's potential for high-temperature optoelectronic applications.