Ionic Conductivity of Yttrium Fluoride and Lutetium Fluoride

At the transitions from the low-temperature orthorhombic forms of lutetium fluoride and yttrium fluoride to the high-temperature hexagonal forms, there are increases of several orders of magnitude in the ionic conductivities. In the high-temperature phases the conductivities are comparable to those of typical ionic melts. These fluoride compounds are therefore solid electrolytes.