Neutron diffraction study of the Pb1-xAlxF2+x solid solution

Powder neutron diffraction studies have been carried out on the fluorite-ty pe Pb1-xAlxF2+x (0 less than or equal to x less than or equal to 0.12) soli d solution. Three interstitial sites, F', F " and F''', were observed, in a ddition to the normal F-n sites of the fluorite structure at (1/4,1/4,1/4). Four types of fluoride sites, F-n, F', F " and F''', were identified with the four sublattices (F-n)(Pb), (F-ra)(Al), (F-i)(Pb) and (F-rd)(Al) sugges ted from F-19- and Al-27-NMR investigations. The clustering process propose d in Pb1-xAlxF2+x on the basis of NMR results is confirmed and the cluster characteristics are determined. (C) 2000 Elsevier Science B.V. All rights r eserved.