1. Upconversion luminescence and favorable temperature sensing performance of eulytite-type Sr3Y(PO4)3:Yb3+/Ln3+ phosphors (Ln=Ho, Er, Tm).
- Author
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Liu, Weigang, Wang, Xuejiao, Zhu, Qi, Li, Xiaodong, Sun, Xudong, and Li, Ji-Guang
- Subjects
ERBIUM ,THULIUM ,LUMINESCENCE ,PHOTON upconversion ,PHOSPHORS ,TEMPERATURE ,MOLECULAR spectroscopy - Abstract
Phase-pure eulytite-type Sr
3 Y0.88 (PO4 )3 :0.10Yb3+ ,0.02Ln3+ upconversion (UC) phosphors (Ln = Ho, Er, Tm) were synthesized via gel-combustion and subsequent calcination at 1250°C. Their UC luminescence, temperature-dependent fluorescence intensity ratio of thermally and/or non-thermally coupled energy levels, and performance of optical temperature sensing were systematically investigated. The phosphors typically exhibit green, orange-red and blue luminescence under 978 nm NIR laser excitation for Ln = Er, Ho and Tm, respectively, which were discussed from two- and three-photon processes. The 524 nm green (Er3+ ), 657 nm red (Ho3+ ) and 476 nm blue (Tm3+ ) main emissions were analyzed to have average decay times of ~52 ± 2, 260.6 ± 0.7 and 117 ± 1 μs, respectively. It was shown that (1) the Er3+ doped phosphor has a better overall performance of temperature sensing with thermally coupled2 H11/2 and4 S3/2 energy levels, whose maximum absolute (SA ) and relative (SR ) sensitivities are ~5.07 × 10−3 K−1 at 523 K and ~1.16% at 298 K, respectively; (2) the Ho3+ doped phosphor shows maximum SA and SR values of ~0.019 K−1 (298–573 K) and 0.42% at 573 K for the non-thermally coupled energy pairs of5 F5 /(5 F4 ,5 S2 ) and5 I4 /5 F5 , respectively; (3) the Tm3+ doped phosphor has a maximum SA of ~12.74 × 10−3 K−1 at 573 K for the non-thermally coupled3 F2,3 /1 G4 energy levels and a maximum SR of ~1.74% K−1 at 298 K for the thermally coupled3 F2,3 /3 H4 levels. Advantages of the current phosphors in optical temperature sensing were also revealed by comparing with other typical UC phosphors. Phase-pure eulytite-type Sr3 Y0.88 (PO4 )3 :0.10Yb3+ ,0.02Ln3+ upconversion (UC) phosphors (Ln=Ho, Er, Tm) were synthesized via gel-combustion, whose property and mechanism of UC luminescence and the performance of optical temperature sensing with thermally and/or non-thermally coupled energy levels were thoroughly investigated. [ABSTRACT FROM AUTHOR]- Published
- 2019
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