Ultra-high sensitivity of multicolor Sm-doped LiSrVO phosphors for contactless optical thermometers.

To overcome the existing challenge of temperature monitoring with high accuracy, we designed Sm-doped LiSrVO phosphors with ultra-high sensitivity as promising candidates for optical thermometers. The prepared samples could emit multicolor emissions after excitation at 343 nm and the optimum doping concentration for the Sm ions in the selected host was 1 mol%. The mechanism of energy transfer from the VO group to the Sm ions was studied and its efficiency was proved to be 84.1% for an Sm ion content of 7 mol%. Based on the disparate thermal quenching performances of the VO group and Sm ions, the temperature monitoring ability of the prepared compounds was examined. Through choosing different emissions of Sm ions, and then combining them with the VO group, optical thermometers with controllable sensitivity were realized. The maximum absolute and relative sensitivities of the resultant phosphors could reach ultra-high values of 1.076 K and 6.167% K, respectively, which were the highest sensitivities reported so far. Furthermore, the doping content also impacted the sensitivities of the resultant compounds.