Optical Temperature Sensing Using Upconversion Fluorescence Emission In Tm³⁺,Yb³⁺ Co-doped NaLuF₄ Nanocrystals

Optical temperature sensors based on the fluorescence of rare earth(RE) ions have attracted great interest in recent years. This technique provides a non-contact temperature measurement by probing the temperature dependence of fluorescence intensities. Compared with conventional temperature monitoring devices, fluorescence based thermometry system does not affect the temperature field and is particularly advantageous operating in electromagnetically and thermally harsh environments, such as at electrical power stations, near high power electric transmission lines, and remote temperature detection in buildings on fire. The most common of which are based on the fluorescence intensity ratio(FIR) and fluorescence lifetime of rare earth(RE) ions, the application of rare earth luminescence was also usually, in leds with high internal temperature, therefore, we also focus on the stability of rare earth luminescence with the changing temperature. In this work, We study the optical temperature sensing using using fluorescence emission in Tm3+,Yb3+co-doped Na Lu F4 nanocrystals.In the field of optical temperature sensors, however, Tm3+ is rarely in use. Largely because the upconversion fluorescence of the 3F2 level of Tm3+ are hardly detected. In this paper we prepate Na Lu F4 nanocrystals codoped with Tm3+ Yb3+ irons by the hydrothermal method. From the XRD spectrum of Tm3+ Yb3+ codoped Na Lu F4 nanocrystals, We know it belongs to the orthogonal phase. Under the excitating of 980 nm semiconductor laser, We detected the upconversion fluorescence on the wavelength of 700 nm, which come from the 3F2 level of Tm3+ that is one of the two thermal couped energy levels. Meanwhile,we use level 1G4 and 3F2 in FIR technology, also gain a good result. We use the Oscilloscope test the lifetime of Na Lu F4:Tm3+,Yb3+ nanocrystal from 20℃ to 200℃. And try to find the law between lifetime and temperature.We also prepate Na Lu F4 nanocrystals codoped with Tm3+, Yb3+, Eu3+ irons by the hydrothermal method, which include Eu3+ irons with different density. Bright red-blue light are obtain under the excitation of 976 nm semiconductor laser. We use the i HR-550 spectrograph to detect the the upconversion fluorescence in different temperature. We analyze the thermal stability of the sample by the Arrhenius equation.