Temperature sensing based on the up-conversion emission of Tm3+ in a single KLuF4 microcrystal

The mono-dispersed hexagon microcrystal of KLuF4:24% Yb3+/0.5% Tm3+ with an average particle size of 5 mm has been synthesized by a facile hydrothermal method. Based on the fluorescence intensity ratio (FIR) technique, the dependence of the up-conversion (UC) emission intensity of a single KLuF4:24%Yb3+/0.5%Tm3+ particle on the ambient temperature ranging from 303 to 503 K has been studied in detail. The sensitivity of the (1)G4(a)/(1)G(4)(b) and F-3(2,3)/H-3(4) thermally coupled levels (TCLs) is calculated, and the maximum sensitivity of which is 2.101 X 10(-3) K-1 at 303 K and 1.451 x 10(-4) K-1 at 503 K, respectively. Furthermore, the temperature of KLuF4:24% Yb3+/0.5% Tm3+ single-particle rise from 347 to 366 K when the pump power increases from 168 to 1145 mW. It proves the heating effect of F-3(2,3)/H-3(4) TCLs is induced by 980 nm laser excitation. Compared with (1)G(4)(a)/(1)G(4)(b) TCLs, the sensitivity of F-3(2,3)/H-3(4) TCLs exhibits better accuracy at high temperature. Moreover, the excellent thermal stability of the KLuF4:24% Yb3+/0.5% Tm3+ microcrystal for temperature detection in the range of 303-503 K is proved. The Yb3+/Tm3+ codoped KLuF4 single-particle shows promising applications in the fields of compact optical thermometers and optical heaters. (C) 2017 Elsevier B.V. All rights reserved.