Synthesis, thermal properties, ion mobility, and conductivity in non-stoichiometric phases (NH4)2-xZrF6-x (0 < x ≤ 0.25)

Abstract

Thermal properties, ion mobility, and conductivity of non-stoichiometric phases (NH4)1.97ZrF5.97, (NH4)1.83ZrF5,83, and (NH4)1.75ZrF5.75 in the temperature range 150–450 ​K have been studied using the TG-DTA, 19F, 1H NMR, and impedance methods. A corrected analysis of the earlier described NMR data for the compound (NH4)2ZrF6, on which basis non-stoichiometric phases (NH4)2-xZrF6-x (0 < x ​≤ ​0.25) were synthesized, has been presented. The types of ion motions have been determined and the mechanisms of their emergence in non-stoichiometric phases have been suggested. It has been established that high ionic conductivity in the studied samples (>4 ​× ​10−3 ​S/cm, T ​= ​413 ​K) is determined by the translational diffusion of F− and NH4+ ions and indicates that the non-stoichiometric phases belong to the family of superionic conductors.