Xie Xiaoyu, Wang Wang, Chen Haoran, Yang Run, Wu Han, Gan Dechao, Li Bin, Kong Xianggui, Li Qiqing, Chang Yulei
State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun 130033 Jilin China
University of the Chinese Academy of Sciences Beijing 100049 China.
RSC Adv. 2023 Mar 14;13(13):8535-8539. doi: 10.1039/d3ra00716b.
Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted great attention in temperature sensing because of their widespread thermal quenching effect (TQE), a phenomenon in which luminescence intensity decreases as the temperature increases. However, enhancing the TQE of activated ions without changing the dopants or the host is still challenging. Herein, Yb and Er codoped UCNPs in a cubic CaGdF host were synthesized by a coprecipitation method for optical temperature sensing. Compared with the homogeneous shell (CaGdF), those heterogeneous (CaF) shelled UCNPs exhibited stronger upconversion luminescence (UCL) due to the significantly reduced multiphonon nonradiative relaxation. Further, we investigated the effects of homogeneous and heterogeneous shells on TQE. The relationship between the intensity ratio of the green emission bands of Er ions (H → I and S → I) and temperature are obtained for these two core@shell UCNPs. The results demonstrated that the UCNPs with CaF shells are more sensitive to temperature in the 200-300 K. The maximum thermal sensitivity of CaGdF:Yb,Er@CaF could reach 2.2% K at 200 K. These results indicate that the heterogeneous core@shell UCNPs are promising for use as optical temperature sensors.
镧系掺杂的上转换纳米粒子（UCNPs）因其广泛存在的热猝灭效应（TQE）而在温度传感领域备受关注，热猝灭效应是一种发光强度随温度升高而降低的现象。然而，在不改变掺杂剂或基质的情况下提高激活离子的热猝灭效应仍然具有挑战性。在此，通过共沉淀法合成了立方相CaGdF基质中Yb和Er共掺杂的UCNPs用于光学温度传感。与均匀壳层（CaGdF）的UCNPs相比，那些具有异质（CaF）壳层的UCNPs由于多声子非辐射弛豫显著降低而表现出更强的上转换发光（UCL）。此外，我们研究了均匀壳层和异质壳层对热猝灭效应的影响。获得了这两种核壳结构UCNPs中Er离子绿色发射带（H→I和S→I）的强度比与温度之间的关系。结果表明，具有CaF壳层的UCNPs在200 - 300 K范围内对温度更敏感。CaGdF:Yb,Er@CaF在200 K时的最大热灵敏度可达2.2% K。这些结果表明，异质核壳结构的UCNPs有望用作光学温度传感器。
