A spatial/temporal dual-mode optical thermometry based on double-sites dependent luminescence of Li4SrCa(SiO4)2: Eu2+ phosphors with highly sensitive luminescent thermometer

Increasing demand for non-contact temperature sensing, in this paper, Li 4 SrCa(SiO 4 ) 2 (LSCS) phosphor doped with Eu 2+ was prepared, and the temperature dependence of its optical properties was studied in detail. The conformation of Eu 2+ double-sites in LSCS host has been veritied by X-ray diffraction (XRD) spectrum, photoluminescence spectra and decay curves. The temperature dependence of emission intensity and decay lifetime of Eu 2+ in the range of 303 K–473 K has been studied systematically. Under the excitation of ultraviolet light (at 363 nm), the color of LSCS: x Eu 2+ ( x  = 0.05) phosphor gradually changed from blue-violet (at 303 K) to light yellow (at 473 K) with the increase of temperature. The highest absolute sensitivity ( S a ) of the material is 0.051 K −1 (at 473 K) and the relative sensitivity ( S r ) is 3.18% K −1 (at 423 K) under fluorescence intensity ratio (FIR) detection technology. In addition, the temperature resolution ranges from 0.17 to 0.35 K. Based on fluorescence lifetime thermometry, the maximum of S a is 1.47 K −1 (at 363 K) and S r is 15.0% K −1 (at 573 K), obviously superior to the previously reported inorganic optical thermometry materials. Moreover, LSCS: Eu 2+ has good signal recognition ability because of the different response of the two emission centers to temperature. Therefore, we believe that LSCS: Eu 2+ has a good application prospect in the field of spatial/temporal optical temperature measurement.