Luminescent hybrid materials based on nanodiamonds (NDs) and rare earth ions have been successfully synthesized by covalently modifying NDs with pyromellitic acid (PMA) which is capable of coordinating to Eu3+ and Tb3+ ions. With NDs acting as a host matrix, the PMA and rare earth ions serve as an organic sensitizer and activator, respectively, yielding a highly bright hybrid composite. Interestingly, for the co-doped hybrid composites ND-PMA-Eu/Tb, the intensity ratio of the two emissions, 5D4 → 7F5 transition (Tb3+) to 5D0 → 7F2 transition (Eu3+), is linearly related to temperature in the range from 77 K to 277 K. Therefore, the hybrid could be developed as a self-calibrated ratiometric luminescent thermometer due to its temperature-dependent luminescence performance.
Rare earth (RE 3+ )-doped phosphors generally suffer from thermal quenching, in which their photoluminescence (PL) intensities decrease at high temperatures. Herein, we report a class of unique two-dimensional negative-thermal-expansion phosphor of Sc 2 (MoO 4 ) 3 :Yb/Er. By virtue of the reduced distances between sensitizers and emitters as well as confined energy migration with increasing the temperature, a 45-fold enhancement of green upconversion (UC) luminescence and a 450-fold enhancement of near-infrared downshifting (DS) luminescence of Er 3+ are achieved upon raising the temperature from 298 to 773 K. The thermally boosted UC and DS luminescence mechanism is systematically investigated through in situ temperature-dependent Raman spectroscopy, synchrotron X-ray diffraction and PL dynamics. Moreover, the luminescence lifetime of 4 I 13/2 of Er 3+ in Sc 2 (MoO 4 ) 3 :Yb/Er displays a strong temperature dependence, enabling luminescence thermometry with the highest relative sensitivity of 12.3%/K at 298 K and low temperature uncertainty of 0.11 K at 623 K. These findings may gain a vital insight into the design of negative-thermal-expansion RE 3+ -doped phosphors for versatile applications.
Well-defined probes based on rare earth complexes were prepared by using europium oxide (Eu2O3), gadolinium oxide (Gd2O3), 2-thenoyl trifluoroacetone (TTA), and 1,10-phenanthroline monohydrochloride monohydricrate (phen) as raw materials. Fluorescence spectroscopy was used to determine that 1:1 is the optimal ratio of Eu3+ and Gd3+. So a Eu0.5Gd0.5(TTA)3phen/PMMA temperature sensitive paint was prepared composed of rare earth complexes Eu0.5Gd0.5(TTA)3phen as probe molecules and polymethyl methacrylate (PMMA) as the matrix. The as-prepared Eu0.5Gd0.5(TTA)3phen/PMMA exhibits a strong emission at 617 nm and has fine temperature quenching properties in the range of 20 °C–90 °C. Furthermore, the rate of change of luminescence and temperature sensitivity are enhanced due to doping of Gd3+, illustrating a synergistic effect between Gd3+ and Eu3+.
危险品化学品经营许可证（带存储）