engleski

Structural studies of nanocrystalline SnO_2 doped with antimony: XRD and Mossbauer spectroscopy

A series of Sb-doped SnO_2 samples, with doping levels 0, 3.1, 6.2, 11.9 and 14.0 at% Sb, has been hydrothermally prepared and characterized by X-ray powder diffraction. Diffraction lines were broadened, the line broadening being anisotropic. Both the line broadening and line anisotropy were dependent on the Sb doping level. The samples are tetragonal, space group P4_2/mnm and isostructural with TiO_2(rutile). Sb doping of SnO_2 causes the increase of unit-cell parameters. The structure of pure SnO_2 and of samples containing 6.2 and 11.9 at% Sb has been refined by the Rietveld method. Crystal structure indicated that both Sb^3+ and Sb^5+ are substituted for Sn^4+ in the SnO_2 structure, Sb^3+ being dominant for the investigated doped samples. The samples were also examined by ^119Sn- and ^121Sb-Mossbauer spectroscopy. Mossbauer spectroscopy confirmed the XRD results. Also, the values of the isomer shifts and quadrupole coupling constants indicated that the configuration around the Sb^3+ site includes the presence of the stereochemically active lone pair electrons.

Oxides; Sol-gel growth; X-ray diffraction; Mossbauer spectroscopy; Crystal structure

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