Excellent Sensitive Temperature Sensing Performance Based on Fluorescence Intensity Ratio Technique of Yb3+/Er3+ Codoped Gd-2(WO4)(3)

The efficient upconversion (UC) particles based on fluorescence intensity ratio (FIR) technique are developed for application in novel temperature sensors. Herein, Yb3+/Er3+-codoped Gd-2(WO4)(3) particles are prepared by coprecipitation method and subsequent calcination. The phase structure and surface morphology of the particles are systematically analyzed. The UC emission spectrum of Gd-2(WO4)(3):Yb3+/Er3+ particles are mainly composed of two strong emission bands centered at 530 and 551 nm, respectively. Moreover, the optimum doping concentration of Yb3+ and Er3+ is fixed at 10% and 2%, respectively. UC emission mechanism based on two-photon process is investigated by studying the pump power excitation dependence and fluorescence decay behavior of Gd-2(WO4)(3):10%Yb3+/2%Er3+ particles. The excellent temperature sensing capability of Gd-2(WO4)(3):10%Yb3+/2%Er3+ particles is implemented from thermally coupled levels (TCLs) of Er3+. Notably, the maximum absolute sensitivity (S-a) and relative sensitivity (S-r) based on TCLs by H-2(11/2)/S-4(3/2) levels are 1.39 %K-1 (at 518 K) and 1.18 %K-1 (at 293 K), respectively. As a result, Gd-2(WO4)(3):10%Yb3+/2%Er3+ particles have a great potential for application in noncontact temperature sensors.