Achieving non-contact optical thermometer via inherently Eu2+/Eu3+-activated SrAl2Si2O8 phosphors prepared in air

Abstract Eu2+/Eu3+-activated SrAl2Si2O8 phosphors, which presented blue emission originating from 4f65d → 4f7 transition of Eu2+ ions and red emission arising from 5D0 → 7FJ transition of Eu3+ ions, were synthesized by the traditional solid-state reaction in the air. The photoluminescence intensities of Eu2+ and Eu3+ ions increased with increasing the dopant content and reached their maximum value when the doping concentration was 3 mol%. Moreover, based on the diverse thermal quenching behaviors of Eu2+ and Eu3+ ions, the thermometric performance of the SrAl2Si2O8: Eu2+/Eu3+ phosphors were investigated by fluorescence intensity ratio technology. The maximum absolute sensitivity and relative sensitivities were 0.056 K-1 and 0.30% K−1, respectively, at the temperature of 583 K. Also, the effects of different excitation wavelength and doping concentration on thermometric performance were studied in detail. On the other hand, through analyzing the various responses of the decay time to temperature, the thermometric performances of the Eu2+ and Eu3+ ions were also discussed in the temperature range of 298–573 K. The maximum relative sensitivity of the studied phosphors reached up to 0.22% K−1 at 573 K. These results suggested that the Eu2+/Eu3+-activated SrAl2Si2O8 phosphors had the potential in the field of non-contact optical thermometry.