Cruz-Lopes, LuísaSavariault, J.-MMorais, C.MFernandez, CPedrosa de Jesus, J.DRocha, J2023-01-132023-01-132004Cruz, L. P., Savariault, J.-M., Morais, C. M., Fernandez, C., Pedrosa de Jesus, J. D., & Rocha, J. (2004). Non-stoichiometric mixed lead and tin niobates. Journal of Solid State Chemistry, 177(4), 1549–1558. https://doi.org/10.1016/j.jssc.2003.12.0100022-4596http://hdl.handle.net/10400.19/7543Novel non-stoichiometric mixed lead and tin niobates with the pyrochlore structure have been synthesized via a solid-state route. The materials have been characterized by bulk chemical analysis, single-crystal and powder X-ray diffraction, 207Pb, 119Sn and 93Nb (single and triple quantum) solid-state NMR spectroscopy. The structures of the new non-stoichiometric mixed lead–tin niobate pyrochlore compounds have been Rietveld refined in the cubic system, space group Fd-3m. The steroactivity of the Sn(II) free electron pair leads to the general formula (Sn1.6−xPbx)(Nb2−ySny)O6.6−0.5y, where x (0–1.6) is the Pb(II) and y (0–0.34) is the Sn(IV) contents. 207Pb, 119Sn and (in particular) 93Nb NMR support the isomorphous substitution of tin for lead in the compounds studied. 93Nb triple-quantum magic-angle spinning NMR spectroscopy show that the materials contain, at least, two distinct niobium sites, in a 2:1 population ratio, which may be associated with different sampleengOxidesPyrochloreNiobatTinjournal article2023-01-12cv-prod-150428410.1016/j.jssc.2003.12.0102-s2.0-1642462913