Excellent Color Purity and Luminescence Thermometry Performance in Germanate Tellurite Glass Doped with Eu 3+ and Tb 3+.

Germanate tellurite glasses doped with Eu³⁺ and Tb³⁺ were synthesized by the conventional melt-quenching method. There is no indication of the energy transfer between dopant ions in this host, but the co-dopants exhibit excellent color purity of 100% for Eu³⁺ and 80% for Tb³⁺. The co-doped glass exhibits yellow luminescence. The quantum yield of the Eu³⁺ emission is equal to 23% under 395 nm excitation. The thermal quenching of Eu³⁺ and Tb³⁺ luminescence occurs at different temperature ranges, which enables the thermal sensing properties of the material. The relative fluorescence intensity ratio (FIR) sensitivity of 0.16% K⁻¹ was recorded in the wide range of temperatures spanning from −193 °C up to 0 °C. The temperature dependence of the decay times was also studied. The lifetime-based temperature sensitivity was determined to be 0.95% K⁻¹ at 250 °C for Tb³⁺⁵D₃ level emission and 0.3% K⁻¹ at 225 °C for Eu³⁺⁵D₁ level emission. [ABSTRACT FROM AUTHOR]