engleski

Structural studies of nanocrystalline Sb-doped SnO_2

Antimony-doped tin oxide (ATO) samples with doping level up to 14 at% Sb were hydrothermally prepared and characterized by X-ray powder diffraction as well with ^(121)Sb Mössbauer spectroscopy. The prepared samples were nanocrystalline. Diffraction lines were broadened, the line broadening being anisotropic. The Sb-doping level influenced both the line broadening and the line widths anisotropy. All samples were tetragonal, space group P42/mnm and isostructural with TiO_2 (rutile). Unit-cell parameters increased with Sb content. 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 as-prepared samples. Mössbauer spectroscopy confirmed the XRD results. The sample containing 6.2 at% Sb was additionally annealed at 350, 450 and 550 oC for 1 h. Broadening of diffraction lines increased due to annealing at 350 oC, then decreased upon further heating. The line anisotropy decreased over the whole temperature range. Unit-cell parameters of the annealed sample decreased with the increase in thermal treatment temperature, which suggested that oxidation of Sb^(3+) took place in an-nealing process. Mössbauer spectroscopy showed that Sb^(3+)/Sb^(5+) content ratio decreased upon annealing. It was noticed that the ratio of full-widths at half-maximum (FWHM) for the diffraction lines 110 and 101 is a good indicator of the Sb^(3+)/Sb^(5+) content ratio in the samples.

Sb-doped tin oxyde ; X-ray diffraction ; Moessbauer spectroscopy

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