Optical manometry is a highly promising method for measuring pressure. However, its wider application is limited by the lower sensitivity and influenced by environmental factors. Herein, multi-mode optical pressure sensors based on Eu 2+ -doped Li 4 SrCa(SiO 4 ) 2 phosphors suitable for a variety of complex pressure-measuring environments are designed. The phosphors contain two separate luminescence centers at 443 nm (Eu Sr ) and 584 nm (Eu Ca ), respectively. In the lower pressure range, the emission peak undergoes a massive redshift of 5.19 nm GPa −1 of Eu Ca , which is 14× better than commercially available ruby sensors. In order to improve the pressure response range and the accuracy of pressure measurement, for the first time, a new approach in the pressure readout method in which single Eu 2+ ions doping based on fluorescence intensity ratio (FIR) pressure measurement is realized in designed materials. Meanwhile, the measured full width at half maximum (FWHM) as an indicator of pressure sensor performance also reveals that the sensing performance is d FWHM /d P ≈ 1.23 nm GPa −1 and d FWHM /d P ≈ 0.84 nm GPa −1 for Eu Sr and Eu Ca positions, respectively. Additionally, the structural stability of the phosphor is confirmed by in situ Raman spectrum. The above results indicate that the Li 4 SrCa(SiO 4 ) 2 :0.04Eu 2+ phosphor is a good candidate for multi-mode optical pressure sensors.
Zhongyu Tong,Jiamin Li,Yuqing Yan,Feifeng Huang,Guanyu Zhu,Huanping Wang,Hua Yu,Degang Deng
The development of tunable broadband near-infrared (NIR) fluorescent materials with excellent luminescent properties is still a challenge for the next generation of intelligent NIR light sources. Here, a series of Cr 3+ doped magnetoplum type NIR phosphors were prepared by the high-temperature solid-state method. Their luminescent properties and the methods to broaden the luminescence bandwidth were discussed in detail. In BaAl 12 O 19 : Cr 3+ phosphor, Cr 3+ -Cr 3+ ion pair was constructed based on heavily doped Cr 3+ ions, so as to broaden its spectral emission range. With the increase of Cr 3+ doping concentration, the full width at half maximum (FWHM) of BaAl 12 O 19 : Cr 3+ sample increased from 18.5 nm to 93.7 nm. Furthermore, the crystal field environment of Cr 3+ ions in BaAl 12 O 19 : Cr 3+ phosphors was changed by cationic substitution (Sr 2+ substituted Ba 2+ ion site). The FWHM of NIR emission increases from 49.37 nm to 123.78 nm, and the internal quantum efficiency (IQE) increases from 65.6 % to 76.2 %, with good thermal stability ( I 373 K / I 298 K = 77.3 %). An intense NIR emission of 31.3 mW at 100 mA is produced by the phosphor-converted light-emitting diode (pc-LED), exhibiting a photoelectric efficiency of 15.3 %.
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