Hydrothermal syntheses, luminescent properties, and temperature sensing of monodisperse Tb-doped NaCeF 4 nanocrystals.

Monodisperse Tb-doped NaCeF 4 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 Ce 3+ at 270-370 nm and those of Tb 3+ at 475-700 nm can be observed. The strongest visible emission was observed in NaCeF 4 :20 at% Tb with a quantum yield of 49%. The efficiency of energy transfer from Ce 3+ to Tb 3+ increases with the Tb 3+ doping concentration and reaches 95% for NaCeF 4 :30 at% Tb. The ratio of Tb 3+ emission to Ce 3+ 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.