The Upconversion Luminescence of Ca₃Sc₂Si₃O₁₂:Yb³⁺ ,Er³⁺ and Its Application in Thermometry

To develop novel luminescent materials for optical temperature measurement, a series of Yb3+- and Er3+-doped Ca3Sc2Si3O12 (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 Yb3+ can greatly enhance the emission of Er3+ by effective energy transfer. The prepared Yb3+ and Er3+ co-doped CSS phosphors exhibit green emission bands near 522 and 555 nm and red emission bands near 658 nm, which correspond to the H-2(11/2)& RARR;I-4(15/2), S-4(3/2)& RARR;I-4(15/2), and F-4(9/2)& RARR;I-4(15/2) transitions of Er3+, 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:Yb3+,Er3+ phosphor is not inferior to that of infrared thermal imaging thermometers. Therefore, CSS:Yb3+,Er3+ phosphors have great potential applications in the field of optical thermometry.