NMR, DTA, and Impedance Spectroscopy Studies of Ion Mobility, Phase Transitions, and Ionic Conductivity in K 1- x (NH 4 ) x SbF 4 Crystals

The ion mobility, phase transitions, and ionic conductivity in the crystal phases in the KF-NH4F-SbF3 system were studied by NMR, DTA, and impedance spectroscopy. An analysis of the 19F and 1H NMR spectra showed how the character of ionic motions in the fluoride and proton sublattices changed with temperature. The types and temperature ranges of ionic motions were determined. Diffusion of the fluoride and partially ammonium ions was found to be the dominant form of ionic motion in the high-temperature modifications formed as a result of phase transitions. According to the electrophysical data, the high-temperature K1 − x (NH4) x SbF4 phases (0.05 ≤ x ≤ 0.75) are superionic, their conductivity reaching ∼10−2–10−3 S/cm at 450–500 K.