The Upconversion Luminescence of CaScSiO:Yb,Er and Its Application in Thermometry.

To develop novel luminescent materials for optical temperature measurement, a series of Yb- and Er-doped CaScSiO (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 can greatly enhance the emission of Er by effective energy transfer. The prepared Yb and Er 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→I, S→I, and F→I transitions of Er, respectively. The temperature-dependent behavior of the CSS:0.2Yb,0.02Er 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 at 500 K and a relative sensitivity of 1.34% K at 300 K. We demonstrate here that the temperature measurement performance of FIR technology using the CSS:Yb,Er phosphor is not inferior to that of infrared thermal imaging thermometers. Therefore, CSS:Yb,Er phosphors have great potential applications in the field of optical thermometry.