Optical thermometry and multi-mode anti-counterfeiting based on Bi3+/Ln3+ and Ln3+ doped Ca2ScSbO6 phosphors
A series of novel Bi 3+ /Ln 3+ -activated Ca 2 ScSbO 6 (CSSO) phosphors were synthesized by solid-state method and their luminescent behaviors were investigated in detail. Under the 302 nm excitation, the CSSO:Bi 3+ shows remarkable near-ultraviolet photoluminescence with a peak emission at 365 nm. Eu 3+ -activated CSSO phosphor possesses high efficiency and no obvious reduction of emission intensity even after replacing Sc with Eu completely, which indicates a low-concentration quenching effect. In addition, its emission intensity at 423 K (I 423K ) still maintains 88 % compared with that of at room temperature (I 298K ), indicating good thermostability. In contrast, the CSSO:Bi 3+ phosphor exhibits a significant reduction in emission intensity, maintaining only 49 % of its luminescence at 423 K (I 423K /I 298K ). By codoping Bi 3+ and Ln 3+ (Ln = Eu, Tb, Dy, Sm), the energy transfer was observed from the Bi 3+ to Ln 3+ ions, endowing the CSSO:Bi 3+ , Ln 3+ phosphors with tunable multicolor emissions. Leveraging the differing thermostabilities of the emission spectra for Bi 3+ and Ln 3+ ions, we designed and assessed a range of sensitive optical thermometers. Among these, the CSSO:Bi 3+ , Eu 3+ phosphors exhibited the best performance, boasting maximum absolute and relative sensitivities of 9.96 % K −1 and 2.002 % K −1 , respectively. Additionally, we displayed the multi-mode anti-counterfeiting function of synthesized phosphors, and a multi-color switching system was designed with the advantages of direct visualization and easy identification of encrypted information. These results indicate that Bi 3+ and Ln 3+ coactivated CSSO phosphor has the potential application for non-contact temperature measurement and anti-counterfeiting.
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