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

Abstract

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.