Hyperfine interactions and site occupancy in Sn‐doped In₂O₃ (ITO)

Abstract

The hyperfine interactions in indium-tin-oxide were studied by 119 Sn Mössbauer spectroscopy. Polycrystalline samples with tin contents from 0.5 to 10 at% Sn on the cation sublattice were measured and compared to the results of 111 In and 111m Cd Perturbed Angular Correlation measurements. The Mössbauer data demonstrate that Sn ions are in a 4+ state. The values of the quadrupole splitting, isomer shift and area ratios undergo changes when increasing the Sn content. The tin cations show a strong preference for the B site versus the D site. The occupancy of Sn on each of the two non-equivalent cation sites also harmonizes with neutron diffraction data.

Modeling the structural properties and energies of transparent conducting oxides

“…A decrease in lattice constant is also reported in the work of Frank and Kostlin [23] increasing Sn content for Sn content less than 2 at.%. Similar experimental results are also found in Binczycka1 et al [24]. This may also be attributed to the simple Sn substitution.…”

Origin of High Mobility in Molybdenum-Doped Indium Oxide

“…One quarter of all the cations occupy the 8 b position, with the remaining three-quarters occupying the 24 d positions. In ITO only tin doping on the indium b -sites results in active donors. , We have tested the incorporation of one Mo into the 40 atom primitive cell of In 2 O 3 (i.e., replacing 6.25% of the In atoms) on both the 8 b and 24 d sites. Mo is 0.32 eV more stable on the 8 b site, indicating that it will have a very strong preference at room temperature and above for taking up this site.…”

Resistive CO gas sensors based on In2O3 and InSnOx nanopowders synthesized via starch-aided sol–gel process for automotive applications

“…This situation seems quite similar to the Al 2 O 3 -SnO 2 system described by Sheng et al [37]. EXAFS and 119 Sn Mossbauer data [32] demonstrate that an increasing content of tin leads to a higher ionic character of Sn 4+ bonds and to a preferential occupancy of the site "d" with respect to site "b" in the cubic In 2 O 3 lattice, accounting for more oxygens closer and strongly bonded to the cations at site "d" than to the cations at site "b" [32]. This suggests that the dipolar coupling is the major source of the peak broadening and may explain the downfield resonance (i.e., deshielding), with respect to the reference at −604.3 ppm of a pure cassiterite sample and a different distribution of the NNN (i.e., next nearest neighbours) cations around a still Sn 4+ centre, due to the presence of a variable number of In 3+ ions with a higher ionic radius and smaller electronegativity in comparison to Sn 4+ , which produce an overall compression of the unit cell volume [38,39].…”

“…It is well known that the two oxides form a solid solution if the at.% of tin is less than 11% [30,31]. On the other hand, it was also observed that, starting from tin contents >6 at.%, a small amount of a SnO 2 phase is commonly observed [32][33][34] and possible overload of SnO 2 produces a In 4 Sn 3 O 12 pyrochlore segregation or formation of finely dispersed cassiterite, undetectable by XRD [35]. However, in the case of sol-gel derived materials, an unique phase was reported in literatures [29,36,37] but it must be taken into account that, with Sn/In ratios greater than 1/1, the In 3+ is incorporated into the cassiterite lattice [27].…”