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

Germanate tellurite glasses doped with Eu[sup.3+] and Tb[sup.3+] 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 Eu[sup.3+] and 80% for Tb[sup.3+]. The co-doped glass exhibits yellow luminescence. The quantum yield of the Eu[sup.3+] emission is equal to 23% under 395 nm excitation. The thermal quenching of Eu[sup.3+] and Tb[sup.3+] 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[sup.−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[sup.−1] at 250 °C for Tb[sup.3+] [sup.5]D[sub.3] level emission and 0.3% K[sup.−1] at 225 °C for Eu[sup.3+] [sup.5]D[sub.1] level emission.