Transmission Electron Microscopy Study of Sn-Doped Sintered Indium Oxide

Abstract

Microstructures of Sn-doped sintered indium oxide were investigated by transmission electron microscopy. It was found that Sn-rich nanosized precipitates were formed inside the ITO grains, in addition to the secondary phases of In 4 Sn 3 O 12 formed at grain boundaries. By nanobeam electron diffraction analysis, the crystal structure of the nanosized precipitates was determined to be the fluorite structure, which is different from the bixbyite structure of the ITO matrix. The structural change in the Sn-rich nanosized precipitates can be explained by the insertion of O 2À ions in the vacancy sites of the bixbyite structure during the substitution of In 3þ sites by Sn 4þ .

Phase Selection Enabled Formation of Abrupt Axial Heterojunctions in Branched Oxide Nanowires

“…Such a fluorine indium tin oxide phase has been reported only in the form of nanosized precipitates with ITO grains in polycrystalline samples synthesized at high temperatures (e.g., 1600 °C). 39 Diffuse scattering can be observed in electron diffraction as a result of short-range order of the oxygen-vacancy sublattice, 40,41 and it is characteristic of oxygen deficient fluorite structures found in cubic stabilized zirconia of the type (1 − x)ZrO 2 •xLnO 1.5 where the shape and sharpness of the diffuse scattering depend on the Ln ion. 42 Such a fluorite structure is actually quite unusual in ITO; at low tin doping (less than 6%) the bixbyite structure is preserved while the In 4 Sn 3 O 12 phase usually appears at higher doping levels.…”

“…Detailed electron diffraction analysis along different zone axes (Figure F) further revealed that the ISO phase possesses a fluorite structure (Figure G) with space group (SG) of Fm 3̅ m and the distribution of In and Sn atoms in the lattice is completely random. Such a fluorine indium tin oxide phase has been reported only in the form of nanosized precipitates with ITO grains in polycrystalline samples synthesized at high temperatures (e.g., 1600 °C) . Diffuse scattering can be observed in electron diffraction as a result of short-range order of the oxygen-vacancy sublattice, , and it is characteristic of oxygen deficient fluorite structures found in cubic stabilized zirconia of the type (1 − x )ZrO 2 · x LnO 1.5 where the shape and sharpness of the diffuse scattering depend on the Ln ion .…”