Hydrothermal syntheses, luminescent properties, and temperature sensing of monodisperse Tb-doped NaCeF4 nanocrystals

Monodisperse Tb-doped NaCeF4 nanocrystals were synthesized via a hydrothermal method. The morphology, and room temperature and temperature dependent luminescent properties were investigated. Excited at 254 nm, the emissions of Ce3+ at 270–370 nm and those of Tb3+ at 475–700 nm can be observed. The strongest visible emission was observed in NaCeF4:20 at% Tb with a quantum yield of 49%. The efficiency of energy transfer from Ce3+ to Tb3+ increases with the Tb3+ doping concentration and reaches 95% for NaCeF4:30 at% Tb. The ratio of Tb3+ emission to Ce3+ emission is sensitive to temperature, and the relative sensitivity was calculated to be 1.0% °C−1 at 60 °C. The mechanisms for this thermal dependence were analyzed in terms of non-radiative relaxation and energy migration.