The Upconversion Luminescence of Ca 3 Sc 2 Si 3 O 12 :Yb 3+ ,Er 3+ and Its Application in Thermometry.

To develop novel luminescent materials for optical temperature measurement, a series of Yb ³⁺ - and Er ³⁺ -doped Ca ₃ Sc ₂ Si ₃ O ₁₂ (CSS) upconversion (UC) phosphors were synthesized by the sol-gel combustion method. The crystal structure, phase purity, and element distribution of the samples were characterized by powder X-ray diffraction and a transmission electron microscope (TEM). The detailed study of the photoluminescence emission spectra of the samples shows that the addition of Yb ³⁺ can greatly enhance the emission of Er ³⁺ by effective energy transfer. The prepared Yb ³⁺ and Er ³⁺ co-doped CSS phosphors exhibit green emission bands near 522 and 555 nm and red emission bands near 658 nm, which correspond to the ² H _11/2 → ⁴ I _15/2 , ⁴ S _3/2 → ⁴ I _15/2 , and ⁴ F _9/2 → ⁴ I _15/2 transitions of Er ³⁺ , respectively. The temperature-dependent behavior of the CSS:0.2Yb ³⁺ ,0.02Er ³⁺ sample was carefully studied by the fluorescence intensity ratio (FIR) technique. The results indicate the excellent sensitivity of the sample, with a maximum absolute sensitivity of 0.67% K ^-1 at 500 K and a relative sensitivity of 1.34% K ^-1 at 300 K. We demonstrate here that the temperature measurement performance of FIR technology using the CSS:Yb ³⁺ ,Er ³⁺ phosphor is not inferior to that of infrared thermal imaging thermometers. Therefore, CSS:Yb ³⁺ ,Er ³⁺ phosphors have great potential applications in the field of optical thermometry.