NMR-SPECTROSCOPIC STUDY OF PB-207 IN PURE AND BARIUM DILUTED LEAD PHOSPHATE

P-31 and Pb-207 MAS and static Pb-207 NMR spectra of Pb-3(PO4)(2) and (Pb1-xBax)(3)(PO4)(2) (x = 0.08, 0.12) are analysed. The resonances st emming from different cation sites are correlated with the correspondi ng local symmetry and their oxygen neighbours. The coordination sphere of Pb(1) consists of 12 oxygen atoms and shows characteristics of a n ear-axial arrangement with a comparatively low anisotropy. The tenfold coordinated Pb(2) atoms are located in a more anisotropically-coordin ated site. In Pb-diluted lead phosphate crystals the Pb(2) positions a ppear to be preferentially substituted by barium. There are indication s that the cation distributions in the diluted samples are inhomogeneo us. Furthermore, P-31 MAS NMR experiments indicate a single phosphorus position. (C) 1998 Elsevier Science B.V. All rights reserved.