The temperature and frequency dependences of the 1H nuclear magnetic resonance relaxation times were studied for a bronze with x = 0.23. Data analysis revealed 3 distinct motions. These were the dissociative diffusion of protons, reorientation of NH4+ over very low activation barriers, and short-range hopping of NH4+ along the hexagonal tunnels of the structure. The spectral density function of the hopping, determined by temperature-frequency superposition, was consistent with low-dimensional motion and indicated an activation energy of about 22kJ/mol.

R.C.T.Slade, P.G.Dickens, D.A.Claridge, D.J.Murphy, T.K.Halstead: Solid State Ionics, 1990, 38[3-4], 201-6