Solid State Ionics, Vol.100, No.3-4, 233-240, 1997
Short-Range Order and F- Ion Diffusion Inside the Pb1-Xalxf2+x Solid-Solution .1. F-19-NMR Investigation
A F-19-NMR investigation of the Pb1-xAlxF2+x (0 less than or equal to x less than or equal to 0.12) solid solution and of the ordered Pb9Al2F24 phase is undertaken as a function of temperature. Several F-ion groups become progressively mobile at the NMR time scale at increasing temperature, the first, (F-i)(Pb) and (F-n)(Pb), are located in the surroundings of Pb2+ cations, the second ones, (F-rd)(Al) and (F-ra)(Al), in that of Al3+ cations. Four types of fluoride ions are distinguished in the F-19-NMR spectra of rigid lattice at low temperature (T = 175 K) and the distribution of fluoride ions among the four sites is determined by deconvolution of the spectra registered. The sites occupied by the (F-n)(Pb) anions an identified with the normal anionic sites of the fluorite network, the others with different interstitial sites.