The ionic transport and diffusion of F− in solid solutions, Pb1−xCrxF2+x (x = 0 to 0.12), with a fluorite-type structure were studied by using impedance spectroscopy and 19F nuclear magnetic resonance methods. The electrical parameters were compared with those of Pb1−xAlxF2+x (x = 0 to 0.12), whose structure was also of fluorite type. The substitutional Cr3+ cation was slightly larger than the Al3+ cation, but both cations had the same coordination of 6 in the ternary fluorides. A comparison of the 19F NMR spectra of Pb1−xMxF2+x (M = Al, Cr), at various temperatures, was made in order to decide whether the clustering process proposed for Pb1−xAlxF2+x was also applicable to Pb1−xCrxF2+x.

Ionic Conductivity Properties and 19F NMR Investigation of Pb1−xCrxF2+x Solid Solutions with Fluorite-Type Structure. M.El Omari, J.Sénégas, J.M.Réau: Solid State Ionics, 1999, 116[3-4], 229-39