Structural Studies of Tin-Doped Indium Oxide (ITO) and In4Sn3O12

Structural changes in the indium oxide lattice due to doping with Sn4+(ITO) were studied by Mossbauer spectroscopy, EXAFS, and neutron powder diffraction. There is a decrease in electrical conductivity as the tin content and oxygen partial pressure increase, which is related to a distortion in the first Sn–O shell. Doping with tin increases the oxygen/cation ratio and the lattice parameter and decreases the Sn–O distances, which disorders the host network. The low-conduction In4Sn3O12phase precipitates when the tin content exceeds 6 at.%. In4Sn3O12is rhombohedral (space groupR3,a=9.4604(2) A, andc= 8.8584(2) A in a hexagonal basis). There is a cation ordering with octahedral sites fully occupied by tin, the tin sites being equivalent in both highly doped ITO and In4Sn3O12.