Ratiometric luminescence thermometry based on diverse thermal response from excited states in La2ZnTiO6: Tb3+

An excited-state thermometer was designed based on the difference in thermal change tendency of the excitation bands in double-perovskite La 2 ZnTiO 6 : Tb 3+ phosphor. The temperature dependent excitation spectra monitored at Tb 3+ 543 nm emission revealed that the 4f 8 →4f 7 5d and Tb 3+ –Ti 4+ intervalence charge transfer (IVCT) excitation bands descended faster with rising temperature in contrast to the case of 4f–4f excitation peaks. The primary cause was analyzed by considering the relationship between the depopulating process and excitation wavelength. Moreover, the excitation intensity ratio of 7 F 6 → 5 D 3 versus IVCT can be used for thermometry with maximal absolute and relative sensing sensitivities of ∼4.46 × 10 −2 K −1 and 0.727% K −1 , indicating the potential for temperature sensing applications. • Thermal quenching rates of Tb 3+ emissions in La 2 ZnTiO 6 alter with excitation lines. • Thermal stability of 4f-4f excitation peaks is better than that of 4f.→5d and IVCT ones. • Excitation intensity ratio of 7 F 6 .→ 5 D 3 to IVCT (or 4f→5d) can be applied for sensing.