Temperature-controlled down-conversion luminescence behavior of Eu³⁺ -doped transparent MF₂ (M = Ba, Ca, Sr) glass...

Eu³⁺ -doped transparent glass ceramics containing MF₂ (M = Ba, Ca, Sr) nanocrystals were fabricated using a melt-quenching method, and the resulting structures were studied using X-ray diffraction. Levels ⁵ D₁ and ⁵ D₀ of Eu³⁺ ions were verified as thermally coupled levels using the fluorescence intensity ratio method. The fluorescence intensity ratios, optical temperature sensitivity and thermal quenching ratios of the transparent glass ceramics were studied as a function of temperature. With an increase in temperature, the relative sensitivity (S_R ) decreased sharply at first, then slowly increased, before finally decreasing. The minimum S_R values of GCBaF₂ (GCB), GCCaF₂ (GCC) and GCSrF₂ (GCS) were 2.8 × 10^-4 , 0.8 × 10^-4 and 1.9 × 10^-4  K^-1 at 360, 269 and 319 K, respectively. Glass ceramics with an intense emission intensity can be used to convert the measured spectrum into temperature and may have an important role in temperature detectors.