Structure, optical characteristics and temperature sensing performance studies of Cs3YF6: Er3+, Yb3+ up-conversion material with cryolite structure

Towards core-shell engineering for efficient luminescence and temperature sensing

Research on the core-shell design of rare earth-doped nanoparticles has recently gained significant attention, particularly in exploring the synergistic effects of combining active and inert shell layers. In this study, we successfully synthesized 8 types of spherical core-shell Na-based nanoparticles to enhance the efficiency of core-shell design in upconversion luminescence and temperature sensing through the strategic arrangement of inert and active layers. The most effective upconversion luminescence was observed under 980 nm and 808 nm laser excitation using NaYF4 inert shell NaYF4:Yb3+, Er3+@ NaYF4 and NaYF4@ NaYF4:Yb3+, Nd3+ core-shell nanostructures. Moreover, the incorporation of the NaYbF4 active shell structure led to a significant increase in relative sensitivity in ratio luminescence thermometry. Notably, the NaYF4:Yb3+, Nd3+, Er3+@ NaYbF4 core-shell structure demonstrated the highest relative sensitivity of 1.12 %K-1. This research underscores the crucial role of inert shell layers in enhancing upconversion luminescence in core-shell structure design, while active layers play a key role in achieving high-sensitivity temperature detection capabilities.

Optimization of deliquescence-proof perovskite-like Cs3ErF6 phosphor and dual-mode luminescent intensity ratio thermometry

The susceptibility of Cs-based fluorides to deliquescence has led to the fact that lanthanide-doped Cs-based fluorides and their related applications have hardly been reported. Herein, the method to solve the deliquescence of Cs₃ErF₆ and its excellent temperature measurement performance were discussed in this work. Initially, the soaking experiment of Cs₃ErF₆ found that water had irreversible damage to the crystallinity of Cs₃ErF₆. Subsequently, the luminescent intensity was ensured by the successful isolation of Cs₃ErF₆ from the deliquescence of vapor by the silicon rubber sheet encapsulation at room temperature. In addition, we also removed moisture by heating samples to obtain temperature-dependent spectra. According to spectral results, two luminescent intensity ratio (LIR) temperature sensing modes were designed. The LIR mode which can quickly respond to temperature parameters by monitoring single band Stark level emission named as "rapid mode". The maximum sensitivity of 7.362%K^-1 can be obtained in another "ultra-sensitive mode" thermometer based on the non-thermal coupling energy levels. This work will focus on the deliquescence effect of Cs₃ErF₆ and the feasibility of silicone rubber encapsulation. At the same time, a dual-mode LIR thermometer is designed for different situations.