Color tunable Bi3+/Eu3+ co-doped La2ZnTiO6 double perovskite phosphor for dual-mode ratiometric optical thermometry

Rigorous temperature measurement employed to characterize physic-chemical state has compelled scientists to explore more novel materials for contactless optical thermometry, which must overcome the drawbacks of low sensitivity and poor signal discriminability. Here, a novel dual-mode optical thermometer La 2 ZnTiO 6 : Bi 3+ /Eu 3+ is designed, prepared and characterized via XRD , XPS , EPR, SEM, EDS , PL spectra and decay time. Under 350 nm excitation, the energy transfer process from Bi 3+ to Eu 3+ allows the samples to demonstrate adjustable multi-color emissions. The temperature-dependent emission spectra display that the luminescence intensity of Bi 3+ ions decreases quite faster than that of Eu 3+ ions with temperature, leading to a significant chromaticity shift (∆E = 224 ×10 −3 in 293–473 K) visible to naked eyes. Based on fluorescence intensity ratio of Eu 3+ versus Bi 3+ (FIR = I Eu /I Bi ), the sample shows the maximum relative sensitivity (S r ) of ~1.50% K −1 at 293 K and excellent signal discriminability. Meanwhile, the 5 D 0 → 7 F 2 transition of Eu 3+ ions shows a thermal-responsive lifetime with the optimal S r of 1.23% K −1 at 573 K. This work suggests that the La 2 ZnTiO 6 : Bi 3+ /Eu 3+ double perovskite phosphor has a great potential for dual-mode optical thermometry, being beneficial to obtain precise, sensitive and reliable temperature detection.