Controlled synthesis of cubic NaYF4:Yb/Er@NaYF4 core/shell nanocrystals for ratiometric fluorescence temperature sensing

Fluorescence intensity ratio (FIR)-based temperature-sensing strategy with self-referencing characteristics exhibits superior accuracy, which attracts great attentions in the electromagnetically and/or thermally harsh environments. The Yb/Er copded hexagonal NaYF4 thermometers are extensively studied, while there is rarely study on the temperature sensing performance of the Yb/Er copded cubic NaYF4–based core/shell nanocrystals (NCs). Herein, the lanthanide doped cubic NaYF4 core and core/shell NCs were successfully prepared by a solvothermal method. The microstructures could be tuned by changing the reaction temperature, NaOA and NH4F concentrations. Our results revealed that the shell thickness was increased with an increase of the reaction temperature. The maximum Sr of 1.02 % K−1 at 313 K and Sa of 0.0045 K−1 at 413 K are achieved in the cubic NaYF4: 20Yb2Er@NaYF4 core/shell NCs, which show promising applications in the temperature sensing field. This work provides important information for the controlled synthesis of cubic lanthanide doped NaYF4 core and core/shell NCs via solvothermal method.