A 19F nuclear magnetic resonance investigation was made of Pb1-xAlxF2+x (x = x to 0.12) solid solutions, and of the ordered Pb9Al2F24 phase, as a function of temperature. Several F−-ion groups became increasingly mobile, at the nuclear magnetic resonance time-scale, with increasing temperature. The first, (Fi)pb and (Fn)pb, were located around Pb2+ cations. The second, (Frd)AI and (Fra)Al, were located in the vicinity of Al3+ cations. Four types of fluoride ion were identified in the 19F nuclear magnetic resonance spectra of the rigid lattice at 175K. The distribution of the fluoride ions among the 4 sites was deduced by deconvolution of the spectra. The sites which were occupied by the (Fn)pb anions were found to be the normal anionic sites of the fluorite network. The others were associated with different interstitial sites.

Short-Range Order and F− Ion Diffusion in the Pb1−xAlxF2+x Solid Solution I - 19F-NMR Investigation. M.El Omari, J.Senegas, J.M.Réau: Solid State Ionics, 1997, 100[3-4], 233-40