Raman scattering features of lead pyroantimonate compounds. Part I: XRD and Raman characterization of Pb(2)Sb(2)O(7) doped with tin and zinc

Yellow pyroantimonates Pb-Sb, Pb-Sb-Sn and Pb-Sb-Zn were synthesized by solid-state reactions at high temperature and characterized by X-ray diffraction and Raman spectroscopy. The lattice size of cubic pyrochlores increases with Sri and Zn doping and with Pb overstoichiometry, indicating the replacement of Sb(5+) by the larger cations. This fact permits the understanding of the corresponding Raman spectral modifications as a consequence of the changes in the local symmetry of the Sb-O polyhedra, justifying the exploitation of Raman spectroscopy to noninvasively identify structural modifications of pyroantimonate pigments in artworks.