Novel Ca 2 ScNbO 6 (CSNO): Cr 3+ phosphors were synthesized through a solid-phase method. The crystal structures, luminescence performances, and applications were introduced in this work. The optimized doping concentration was found with a Cr 3+ concentration of 0.01 mol. Under the 336 nm excitation, the recorded photoluminescence spectrum in the range of 650–1300 nm indicated that the obtained sample can emit a broad near-infrared emission with a dominant peak of 858 nm while the full width at half maximum (FWHM) was determined to be 191 nm. To gain a deeper comprehension of the luminescent properties, the crystal field strength was investigated as Dq/B = 2.03, and the electron-phonon coupling for parameter S was calculated to be about 2.01. As for the potential application, utilizing the variable temperature decay lifetime technique, the relative sensitivity (S R ) was approximately 1.16% K −1 at 387 K, which can be promised for utilization in optical temperature measurement. On the other hand, a near-infrared phosphor-converted lighting-emitting diode ( Pc -LED) was fabricated for night vision. Eventually, the security ink based on the obtained sample was made for use in the anti-counterfeiting field.
Developing novel optical thermometry with ultrahigh relative sensitivity and temperature resolution has become a cutting-edge topic. For this purpose, under obeying Boltzmann distribution , a series of Li 2 Zn 0.9992-x A x Ge 3-y B y O 8 :0.08% Cr 3+ (B= Sc 3+ , In 3+ , A = Si 4+ ) phosphors were studied, which the luminescence intensity ratio between the transition of 4 T 2g → 4 A 2g emission and the R line based on thermally coupled energy levels constitutes a temperature sensing work with a relative sensitivity of 9.46% K −1 , 9.73% K −1 , and 10.38% K −1 , respectively. It is worth mentioning that the luminescence intensity of the R line (peak 1) increases significantly with the increase of temperature, while the transition of 4 T 2g → 4 A 2g (peak 2) with high intensity at low temperature gradually quenching, and this opposite trend is an important advantage for the design of excellent thermometers. Compared the best relative sensitivity of Li 2 Zn 0.9992-x A x Ge 3-y B y O 8 :0.08%Cr 3+ (B= Sc 3+ , In 3+ , A = Si 4+ ) with the crystal field Dq /B, it can be concluded that relative sensitivity increasing gradually with decreasing the intensity of crystal field. Finally, by testing the stability of the sample at 50 K, a thermal resolution of 0.082 K, 0.080 K and 0.077 K was obtained, respectively, which is one of the best thermal resolutions so far, while the repeatability of the sample stability at 50 K and 300 K cycles was higher than 99%. Our work is expected to provide guiding insights for optimizing the sensitivity of Cr 3+ -based luminescence intensity ratio thermometers.
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