Multichannel luminescence of Eu2+/Eu3+ Co-activated Ca9Mg1.5(PO4)7 phosphors for self-referencing optical thermometry

Abstract Eu 2+ /Eu 3+ co-doped Ca 9 Mg 1.5 (PO 4 ) 7 phosphors are prepared through a convenient solid phase reaction, and their optical characteristics were studied to investigate the possible applications in luminescence thermometric field. The conformation of Eu 2+ and Eu 3+ dual-emitting centers in Ca 9 Mg 1.5 (PO 4 ) 7 host was veritied by X-ray photoelectron spectroscopy, photoluminescence spectra and decay curves. In Eu 2+ /Eu 3+ co-activated Ca 9 Mg 1.5 (PO 4 ) 7 thermometric phosphor, not only the Eu 2+ -blue emission and Eu 3+ -red emission, but also the double-sites emissions in blue and red regions of Eu 2+ ions can be used as FIR signals. Moreover, the exhaustive mechanism is discussed in depth with the measured data, and the intense temperature dependence is interpreted in the light of thermal-quenching. Additionally, benefited from their diverse thermal quenching behavior, the fluorescence intensity ratio (FIR) of Eu 3+ to Eu 2+ displays remarkable linear temperature-dependent and the maximum sensitivity is 8.40 × 10 −5  K −1 for the obtained phosphors. Moreover, the FIR of Eu 2+ ( I 600 ) to Eu 2+ ( I 415 ) is fitted very well, and the maximum value of S r is 1.192% K −1 at 383 K, as well as the value of S a is 0.064 K −1 . As a consequence, this work indicates that Ca 9 Mg 1.5 (PO 4 ) 7 : Eu 2+ /Eu 3+ phosphors could be widely applied in optical temperature sensors.