Nd³⁺, Yb³⁺:YF₃ Nanosensors for Luminescent Thermometry

The thermometric characteristics of Nd³⁺ (0.5 mol %), Yb³⁺ (0.1; 0.5; 1.0 and 2.0 mol %):YF₃ nanoparticles obtained by hydrothermal method are reported. The nanoparticles had a size of 234 ± 13 nm. The luminescence intensity ratio (LIR = I_Nd (⁴F_3/2 – ⁴I_9/2, ∼866 nm)/I_Yb(²F_5/2 – ²F_7/2, ∼1000 nm) of Nd³⁺ and Yb³⁺ emissions in the temperature range of 300–500 K was used as a temperature-dependent parameter. The LIR function exhibited a monotonic shape, which is advantageous for the application of luminescent thermometry. The maximum relative sensitivity was achieved for Nd³⁺ (0.5 mol %), Yb³⁺ (1.0 mol %):YF₃ (0.168% K^–1 at 300 K).