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 powd er 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 ox ygen/cation ratio and the lattice parameter and decreases the Sn-O dis tances, which disorders the host network, The low-conduction In4Sn3O12 phase precipitates when the tin content exceeds 6 at.%, In4Sn3O12 is rhombohedral (space group R (3) over bar, a = 9.4604(2) Angstrom, and c = 8.8584(2) Angstrom in a hexagonal basis), There is a cation orderi ng with octahedral sites fully occupied by tin, the tin sites being eq uivalent in both highly doped ITO and In4Sn3O12. (C) 1998 Academic Pre ss.