Optical thermometry based on temperature-dependent luminescence of Eu2+/Tb3+/Eu3+ Co-doped BaO-ZnO-P2O5-B2O3 glasses

Developing luminescent materials with lower cost and higher temperature sensitivity can provide more options for achieving precise optical thermometry. Therefore, the Tb 4 O 7 and Eu 2 O 3 co-doped BaO-ZnO-P 2 O 5 -B 2 O 3 glasses for optical thermometry were designed and synthesized using a high-temperature melting and quenching method. Due to the low optical basicity and the formation of defects of the glasses, the coexistence of Eu 2+ and Eu 3+ ions was achieved without the reducing agent. In Eu 2 O 3 doped glasses, the relative content variation of Eu 2+ and Eu 3+ ions was analyzed using high-resolution X-ray photoelectron spectroscopy. Emission spectra and fluorescence lifetimes confirmed the effective energy transfer processes between Eu 2+ and Tb 3+ or Tb 3+ and Eu 3+ , which play critical roles in the tunable white emission properties of the material. In the temperature-dependent fluorescence spectra, Eu 2+ ions exhibit significant thermal quenching behavior, which is key to achieving higher temperature sensitivity in optical thermometry. The Eu 2+ /Tb 3+ /Eu 3+ co-doped glasses were investigated for their optical temperature sensing behavior, utilizing the fluorescence intensity ratio techniques, within the temperature range of 273 K–498 K. The maximum absolute (at 498 K) and relative (at 273 K) sensitivity based on the fluorescence intensity ratio, were observed for Eu 2+ /Eu 3+ pairs were 0.145 K −1 and 1.46 % K −1 , respectively, outperforming the conventional Tb 3+ /Eu 3+ combination. Additionally, no significant fluctuation occurred during the repeated experiment. This work demonstrates that Eu 2+ /Tb 3+ /Eu 3+ co-doped BaO-ZnO-P 2 O 5 -B 2 O 3 glasses could be considered a promising candidate for optical thermometry.