Multichannel luminescence properties and ultrahigh-sensitive optical temperature sensing of mixed-valent Eu2+/Eu3+ co-activated Ca8ZrMg(PO4)6(SiO4) phosphors

A novel dual-emitting Ca 8 ZrMg(PO 4 ) 6 (SiO 4 ): (Eu 3+ , Eu 2+ ) phosphors with ultrahigh-sensitive optical temperature sensing are prepared by a conventional solid-state method. The Eu 2+ /Eu 3+ co-activated Ca 8 ZrMg(PO 4 ) 6 (SiO 4 ) phosphors exhibit efficient dual-mode emissions with an intense, broad blue emission peaked at 414 nm and a relative bright red-emitting centered at 614 nm under 297 nm UV-light excitation, respectively. Furthermore, the fluorescence intensity ratio (FIR) technology is applied to analyse the optical temperature sensing performance of Ca 8 ZrMg(PO 4 ) 6 (SiO 4 ): (Eu 3+ , Eu 2+ ) phosphors. Based on different thermal quenching behavior of Eu 2+ and Eu 3+ dual-emitting centers, linear temperature-dependent FIR between Eu 2+ and Eu 3+ is obtained. The maximal absolute sensitivity reaches as high as 5.94% K −1 , which is superior to that for the other luminescent temperature sensing materials reported previously. Analyses of the temperature-dependent photoluminescence spectra and configurational coordinate diagrams for Ca 8 ZrMg(PO 4 ) 6 (SiO 4 ): (Eu 3+ , Eu 2+ ) phosphors indicate that the temperature-sensitive variation in FIR of Eu 2+ to Eu 3+ is originated from the difference in thermal quenching activation energy for 5d→4f transition of Eu 2+ and 5 D 0 → 7 F J (J = 1, 2, 4) transitions of Eu 3+ . These results reveal that the Ca 8 ZrMg(PO 4 ) 6 (SiO 4 ): (Eu 3+ , Eu 2+ ) phosphors show glorious potential in high temperature optical thermometry.