engleski

Structural Study of Sn-doped In_2O_3

Tin doped In_2O_3 (ITO) is widely used in phototronic, opto-electronic and microelectronic devices. There are numerous studies on ITO, but the understanding of its defect structure is rather incomplete. In_2O_3 possesses a cubic structure, the space group Ia-3 [1]. The structure contains two different six-fold-coordinated cation sites referred as sites B and D, respectively. This paper focuses on X-ray diffraction and ^(119)Sn Moessbauer studies of the polycrystalline ITO samples containing 2-14 at% Sn. Nanocrystalline ITO powders were prepared by a sol-gel technique using InCl_3 and SnCl_4 reagent grade chemicals and annealed at 300^oC for 5 h. Lattice parameter a of doped In_2O_3 increased with Sn-doping level up to 8 at% and decreased above. Such behavior of lattice parameter suggests that tin substitution for In^3+ on sites B and D is non-uniform and depends on tin content. ^(119)Sn Moessbauer spectra indicated that only the Sn^4+ state is present in ITO samples. The least square fitting of spectra was performed by assuming presence of two doublets. In accordance with [2], doublets with isomer shifts (IS) in the range 0.09 to 0.17 and 0.36 to 0.464 mms^-1, respectively, correspond to the D and B sites in the cation sublattice of the In_2O_3 structure. The area ratio of the two doublets depended on tin content.

Sn-doped In_2O_3; X-ray diffraction; Moessbauer spectroscopy

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