Photoluminescence of TTFA-sensitised NaMgF3:Eu Nanoparticles: Energy Transfer and Thermal Quenching for Temperature Sensing

We report the temperature-dependent photoluminescence properties of 2-thenoytrifluoroacetone (TTFA)-sensitised NaMgF 3 :Eu (0.1 mol% to 5 mol%) nanoparticles. Maximum sensitisation was observed for 1%Eu doping, and the sensitised emissions were dominated by highly distorted Eu 3+ ions in the nanoparticle shell region. All Eu 3+ emission s decreased as the temperature increased from 300 K to 460 K. This thermal quenching is well described by a kinetic model featuring thermally-induced back transfer from the Eu 3+ 5 D 0 state to the TTFA T 1 triplet state prior to non-radiative decay. The model places the T 1 state 0.44 eV above the 5 D 0 state and 0.21 eV above the Eu 3+ 5 D 1 state in TTFA-sensitised NaMgF 3 :Eu. The ratio of the magnetic dipole ( 5 D 0 → 7 F 1 ) and forced electric dipole ( 5 D 0 → 7 F 2 ) emission intensities was also temperature dependent. Thus, TTFA-sensitised NaMgF 3 :Eu nanoparticles have potential for both intensity-based and ratiometric photoluminescent nanothermometry with relative sensitivities up to 2.7%/K.