Multiple site occupancy induced yellow-orange emission in an Eu 2+ -doped KSr 6 Sc(SiO 4 ) 4 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 KSr 6 Sc(SiO 4 ) 4 :Eu 2+ phosphor with decorative kröhnkite-like octahedral tetrahedral chains was successfully synthesized. Multiple site occupancy occurred in KSr 6 Sc(SiO 4 ) 4 :Eu 2+ 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 2+ in five Sr 2+ sites. In the meantime, the site occupation preference, energy transfer process, and thermal quenching mechanism of Eu 2+ 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 -1 at 475 K. The phosphor KSr 6 Sc(SiO 4 ) 4 :0.07Eu 2+ presents the potentiality as an optical thermometer.