The Influence of Sample Annealing on the Temperature Sensitivity of YF₃:Tb³⁺, Eu³⁺ Temperature Sensors

The effect of two different post-treatment processing (annealing in air for 4 h at 400°C or annealing in NH₄(HF₂) for 4 h at 400°C) on the spectral characteristics of the samples was investigated. The YF₃:Tb³⁺ (1.0 mol %), Eu³⁺ (0.5, 1.0, 2.0, and 4.0 mol %) samples were prepared using hydrothermal synthesis. The luminescence spectra of the samples in the temperature range of 80–320 K were detected in order to obtain the luminescence intensity ratio (LIR), which is a temperature-dependent parameter. The LIR function exhibited a monotonic behavior, which is advantageous for the use in luminescent thermometry. The sample with the highest temperature sensitivity was YF₃:Tb³⁺ (1.0 mol %), Eu³⁺ (1.0 mol %). The temperature sensitivity for this sample was found to be equal to S_r = 0.44% K^–1 (80–150 K).