Luminescence properties of KBaYSi₂O₇:Ce/Eu-Tb phosphors for multifunctional applications

In this work, the multifunctional KBaYSi₂O₇:Ce/Eu-Tb (KBYS:Ce/Eu-Tb) phosphors were synthesized by using the conventional high-temperature solid-state reaction, and the luminescence properties were investigated for LED and optical thermometer applications. The single-phase samples were checked by x-ray diffractometer patterns. The energy transfer was found in both Eu²⁺-Tb³⁺ and Ce³⁺-Tb³⁺ codoped samples, which was verified by spectra and decay curves. Correspondingly, the tunable emission was realized by adjusting the dopant concentrations and white light was obtained in the KBYS:4%Eu²⁺,9%Tb³⁺ sample, owing to the energy transfers among Eu²⁺, Tb³⁺, and Eu³⁺. By studying the temperature dependence of the KBYS:2%Ce³⁺,7%Tb³⁺, it has been found that the fluorescence intensity ratio for Tb³⁺ and Ce³⁺ emissions changes with temperature, indicating the potential application in an optical thermometer. The high absolute sensitivity was determined to be 0.012  K^-1. By evaluating the thermal quenching luminescence of the KBYS:4%Eu²⁺,9%Tb³⁺, the thermal quenching temperature T_0.5 was determined to be 555 K, implying high thermally luminescent stability.