Multiple site occupancy induced yellow-orange emission in an Eu-doped KSrSc(SiO) phosphor towards optical temperature sensors.

Phosphors have attracted significant interest as potential optical temperature sensors in recent years. In our work, a new blue-light stimulated KSrSc(SiO):Eu phosphor with decorative kröhnkite-like octahedral tetrahedral chains was successfully synthesized. Multiple site occupancy occurred in KSrSc(SiO):Eu and induced a yellow-orange emission band with a peak at 571 nm and an FWHM of 91 nm. Gaussian fitting and time-resolved photoluminescence mapping were combined to analyze the occupation of Eu in five Sr sites. In the meantime, the site occupation preference, energy transfer process, and thermal quenching mechanism of Eu emission centers have been comprehensively examined. Under 450 nm excitation, the optimal sample possesses an acceptable quantum efficiency (EQE = 17.3%) and a high sensitivity between luminescence properties and temperature variation ranging from 200 to 475 K. The optimal sample's relative sensor sensitivity achieves a maximum value of 3.53% K at 475 K. The phosphor KSrSc(SiO):0.07Eu presents the potentiality as an optical thermometer.