Synthesis and Complex Study of Potassium Ammonium Hexafluorozirconates: Ion Mobility, Phase Transitions, and Ionic Conductivity in K_(2-n)(NH_4)_nZrF_6 Compounds as Probed by NMR, DTA, and Impedance Spectroscopy

摘要

The mobility of the fluoride and ammonium ions (180-480 K) in K_(2-n)(NH_4)_nZrF_6 compounds (0.2 < n < 1.80) has been studied by ~(19)F and ~1H NMR. Correlations between the composition of the cationic sublattice, the character of ion motions, and the phase-transition temperature in these compounds have been established. The high-temperature modifications of compounds with n > 1 are characterized by translational diffusion of ions in the fluoride and ammonium sublattices, and their ~(19)F NMR spectra are characterized by uniaxial chemical shift anisotropy. The electrophysical properties of these compounds are studied in the range 300-480 K.