The explanation of abnormal thermal quenching of the charge transfer band based on thermally coupled levels and applications as temperature sensing probes.

Because of thermal quenching, conventional luminescent materials suffer from severe problems when employed at high temperatures. Based on the thermally coupled energy levels (TCLs) of rare-earth ions, we report and explain an abnormal thermal quenching phenomenon in the excited state of the charge transfer band (CTB), which is expected to bring out a solution to the problems of the low sensitivity of temperature-sensing materials and applications at high temperature. Temperature-dependent excitation spectra of Er or Eu-doped CaMoO, CaWO, and LuVO phosphors are recorded.