A multi-mode optical thermometry based on the up-conversion La2MgGeO6: Er3+, Yb3+phosphor

The up-conversion (UC) La2MgGeO6: Er3+, Yb3+ phosphors were prepared by a high-temperature solid-phase method. The structural phase and luminescence characteristics of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence spectra. The research systematically investigated a multi-mode optical thermometry based on fluorescence intensity ratios (FIR) of the thermal-coupled energy levels 2H11/2/4S3/2, non-thermal-coupled energy levels 4S3/2/4F9/2, and the fluorescence lifetime of the 4S3/2 state. Based on these methods, the maximum relative sensitivity reached 1.130%K-1, 0.623%K-1, and 2.914%K-1, respectively. According to the results, the manufactured samples have remarkable temperature measuring performance, which is characterized by a broad temperature measurement range, high sensitivity, and superior stability.