Spectral Characterization of CeF3-YF3-TbF3 Nanoparticles for Temperature Sensing in 80–320 K Temperature Range

The studied Ce0.5Y0.5−XTbXF3 (X = 0, 0.001, 0.002, 0.005, 0.01, and 0.05) nanoparticles were synthesized via the water-based co-precipitation method. All the samples demonstrated diameters in the 17–20 nm range and a hexagonal phase corresponding to the phase of CeF3. Under 266 nm excitation (4f–5d absorption band of Ce3+), the luminescence spectrum shape was notably dependent on temperature. The integrated luminescence intensity ratio (LIR) of Ce3+ and Tb3+ (5D4–7F3) peaks was chosen as a temperature-dependent parameter. It was shown that the LIR functions linearly decay. The rate of decay decreases with the increase in Tb3+ concentration. This was explained by the fact that in the case of low Tb3+ concentrations, the spectral temperature dependence is mostly based on effective thermal quenching of Ce3+ luminescence. At higher Tb3+ concentrations, there is a higher probability of Ce3+ to Tb3+ energy transfer. Here, the efficiency of the temperature dependence of this process is lower, and the rate of LIR decay is lower as well.