Modelling and analyzing the glass-like heat transfer behavior of rare-earth doped alkaline earth fluoride crystals

The heat conduction of solids has always been an important issue in materials science. Some structure-ordered crystals deliver heat transfer characteristics similar to amorphous solids, which endow such crystals with glass-like thermal properties that are attractive and promising in numerous applications. Here, the glass-like thermal behavior as a "three-stage" type inside rare-earth (RE) doped alkaline earth fluoride crystals is reviewed. By modeling and analyzing the thermal conductivity of RE doped CaF2 crystals as a function of temperature and doping concentration, the mechanism of glass-like heat conduction behavior emerging from RE doped fluoride crystals is investigated. The appropriate numerical models to fit the thermal conductivity of RE doped fluorides are proposed and discussed, which paves a theoretical foundation for subsequent similar research.