Peculiarities of ion mobility and conductivity in the (NH4)6LiHf2Zr2F23 compound

Abstract Ion mobility and electrophysical properties in (NH4)6LiHf2Zr2F23 compound have been studied by 1H, 19F NMR, and impedance spectroscopy. The types of ion motions in the fluoride and ammonium sublattices of the compound have been determined in the temperature range 150–450 ​K and their activation energy was estimated. The presence of the order-disorder phase transition in this compound in the temperature range 400–450 ​K with the formation of metastable high-temperature β–modifications, in which diffusion of fluoride and ammonium ions is the dominant type of ionic motion, is established. The value of conductivity at 450 ​K–4.5·10−3 ​S/cm indicates that the compound studied belongs to the class of superionic conductors.