Shuang-Yin Zhu,Dan Zhao,Rui-Juan Zhang,Yan-Ping Fan,Wen Liu
Bi3+/Eu3+ co-doped phosphors can realize multi-color luminescence by adjusting the concentration ratio, which makes it possible to manually control the emission color. On this basis, a series of Bi3+/Eu3+ co-doped phosphors SrLaGa3O7:xBi3+,yEu3+ were prepared. The existence of energy transfer from Bi3+ to Eu3+ was verified by spectral analysis. The emission spectra of SrLaGa3O7:xBi3+ show a wide-band peaking at 472 nm. For SrLaGa3O7:xBi3+,yEu3+, the Bi3+ → Eu3+ energy transfer occurs and a series of sharp emitting peaks of Eu3+ can be observed simultaneously. The relative luminescence intensity of Bi3+ and Eu3+ can be modulated by changing the relative concentrations of Bi3+ and Eu3+. Using this mechanism, the color tunable luminescence of SrLaGa3O7:xBi3+,yEu3+ from cyan, through white to orange, and finally to red is realized. By using a 320 nm UV chip and SLG:0.06Bi3+,0.07Eu3+ white phosphor, a white light-emitting diode (WLED) lamp was fabricated with chromaticity coordinates of (0.3199, 0.3083) and a color rendering index Ra of 82. This indicates that the prepared sample is a very promising candidate in the LED field.
Jiawen Wang,Ruoshan Lei,Shilong Zhao,Feifei Huang,Degang Deng,Shiqing Xu,Huanping Wang
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.
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