Enhanced luminescence and quenching mechanisms in Na⁺ Co-doped K₇CaY₂(B₅O₁₀)₃:Tb 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 D₄ → F₅ 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.