Synthesis and Characterization of Tin Niobates

The synthesis and the structural characterization of tin niobates Sn11x Nb2 O61x , x50.0, 0.5, and 1.0, are reported. The materials have been characterized by bulk chemical analysis, single-crystal and powder X-ray di4raction, and 119Sn Mossbauer and 93Nb and 119Sn solid-state NMR spectroscopies. SnNb2 O6 is a synthetic analog of the rare mineral foordite. Red Sn2 Nb2 O7 crystallizes in a pyrochlore structure with a510.5386 A. 119Sn Mossbauer reveals the presence of both Sn(II) and Sn(IV) in pyrochlore samples. 119Sn MAS NMR spectroscopy supports the presence in synthetic foordite of Sn(II) in eight-fold coordination. The six-coordinated Sn(IV) and eight-coordinated Sn(II) 119Sn MASNMRresonances are not resolved in the Sn2 Nb2 O7 pyrochlore spectrum. 93Nb NMR indicates a fairly distorted local environment for niobium in synthetic foordite, much more so than in the Sn2 Nb2 O7 pyrochlore.N/

Non-stoichiometric mixed lead and tin niobates

Novel 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 sampleinfo:eu-repo/semantics/publishedVersio

Non-stoichiometric mixed lead and tin niobates

International audienceNovel 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 sample domains