High-sensitivity NaYF 4 :Yb 3+ /Ho 3+ /Tm 3+ phosphors for optical temperature sensing based on thermally coupled and non-thermally coupled energy levels

(345 K), and 0.0167 K, respectively, which are better than those of most sensing materials, and the simultaneous action of multiple coupling energy levels can further improve the temperature precision. This study indicates that the sample has a good value for optical temperature measurement and also provides new ideas for the exploration of other high-quality optical temperature sensing materials.