New transparent conductors with the M7O12 ordered oxygen-deficient fluorite structure:: from In4Sn3O12 to In5.5Sb1.5O12

A new transparent conductor, containing pentavalent antimony, In4+xSn3-2xSbxO12, has been synthesized for 0less than or equal toxless than or equal to1.5. The latter exhibits an ordered oxygen-deficient fluorite structure with an ordered distribution of Sb5+ and In3+/Sn4+ species in the octahedral and seven-fold coordinated sites, respectively. More importantly, it is shown that the electronic conductivity of this transparent conducting oxide (TCO) at room temperature, is one order of magnitude larger for x = 1 (In5SnSbO12) than for x = 0 (In4Sn3O12) and it turns to a semi-metallic behavior in contrast to In4Sn3O12 which is a semi-conductor. The potential of this new material, as TCO, is also shown by its reflectance spectra, similar to In4Sn3O12, involving only a small increase of the optical bandgap, by 0.15 eV. (C) 2004 Elsevier Inc. All rights reserved.