An ultra-sensitive fluorescence thermometer: Ca2MgWO6: Tm3+ phosphor

In this study, Tm 3+ -doped Ca 2 MgWO 6 (CMWO) phosphors were prepared and thoroughly analyzed. The structure, luminescent and temperature-dependent behavior of the phosphors were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), photoluminescence (PL) and excitation (PLE) spectra, along with temperature-dependent PL spectroscopy . XRD and SEM analysis confirmed the successful preparation of a pure-phase double perovskite structured Ca 2 MgWO 6 phosphor with successful Tm 3+ doping. The PL spectrum indicates that the phosphor emits light under both 285 nm and 361 nm excitation. The PLE spectrum reveals that the optimal doping concentration of Tm 3+ for 285 nm excitation is 0.007, while for 361 nm excitation, it is 0.08. The phosphor was then tested for variable-temperature emission spectra , and its temperature-sensing performance was evaluated using the fluorescence intensity ratio (FIR) method. Under 361 nm excitation, the CMWO:0.08 Tm 3+ phosphor exhibited a maximum relative sensitivity ( S r(max) ) of 2.33 % K −1 at 348 K, within the temperature range of 198–348 K. When excited at 285 nm, the CMWO:0.007 Tm 3+ phosphor displayed strong temperature dependence in the range of 98–223 K, with an S r(max) of 14.71 % K −1 at 223 K, surpassing many thermometric phosphors reported in the literature. These results highlight the significant potential of CMWO:Tm 3+ phosphors as highly sensitive optical temperature sensors, particularly for low-temperature applications.