The conductivity was measured, at temperatures ranging from ambient to about 400K, by using an alternating-current impedance method. It was found that the conductivity obeyed an Arrhenius relationship. The conductivity at 120K, and the activation energy, were equal to 0.0003S/m and 29kJ/mol. The use of 1H and 19F nuclear magnetic resonance (second-moment, spin-lattice relaxation time) measurements confirmed that the conductivity was due to the diffusion of NH4+ ions.

Y.Furukawa, A.Sasaki, D.Nakamura: Solid State Ionics, 1990, 42[3-4], 223-6