TEMPERATURE DEPENDENCES OF FLUORESCENCE LIFETIMES IN CR-3+-DOPED INSULATING CRYSTALS

The temperature dependences of the fluorescence lifetimes of Cr3+ doped insulating crystals, which have been used as temperature-sensing elements or have such potential uses for different temperature regions, are reviewed in terms of the crystal-field strength. Two single configurational coordinate models are proposed to interpret the temperature dependence of Cr3+ fluorescence in materials with low and high crystal-field strength. The validities of the two models are demonstrated by their close fit to the lifetime data of the Cr3+ fluorescence in appropriate materials. As was shown in thermometric applications, the expressions obtained for the temperature dependence of the fluorescence lifetimes, deduced from the proposed models, are of use as empirical calibration formulae in the assessment of various Cr3+ fluorescence lifetime-based thermometers.