Magic-angle spinning 127I nuclear magnetic resonance studies were made of β-phase powder at temperatures of between 123 and 413K. It was noted that the data were sensitive to Ag+ diffusion through the I lattice. In the case of low-temperature spectra, the I ions appeared to be located in almost static environments; in agreement with the low-temperature crystal structure. At higher temperatures, there was a substantial broadening of the central transition, together with a disappearance of spinning sidebands. The temperature dependence of the central transition linewidth was consistent with the occurrence of 2 types of Ag diffusion, with associated activation energies of 0.17 or 0.0080eV.

G.W.Wagner: Solid State Ionics, 1991, 47[1-2], 143-7