Rare-earth composite as optical upconversion temperature sensor

In this work, rare-earth composite as an optical upconversion temperature dual mode sensing is practically demonstrated. NaGdF4:Yb3+/Er3+/Zn2+ phosphor was synthesized by the solvothermal method. The phase purity, crystal structure and morphologies were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The enhancement of upconversion luminescence is achieved by aliovalent doping in Zn2+ co-doped NaGdF4: Yb3+/Er3+ phosphors. The temperature sensing behaviours based on the luminescence intensity and luminescence lifetime in phosphors are recorded in the temperature range from 75 to 297 K, and the maximum sensitivity is obtained as 13.4 x 10(-3) K-1 at 75 K and 2.52 x 10(-3) K-1 at 225 K, respectively.