Effect of the chemical composition on the sensing properties of In2O3–SnO2 nanoparticles synthesized by a non-aqueous method

In2O3–SnO2 nanocrystals have been synthesized by a non-aqueous sol–gel technique with the aim to test them as sensing element in resistive gas sensors. The whole range of compositions between pure indium oxide and 100% tin oxide, was investigated. XRD, FT-IR, TEM and HRTEM analyses of the synthesized nanopowders give evidence for remarkable structural and sizing variations depending on the tin concentration. In particular, with increasing tin content the mean crystallite size decreases, from 25 nm down to 1–2 nm and, at content higher than 75 wt%, it causes a modification of the lattice structure from cubic to tetragonal.Electrical and sensing tests in dry air have been performed on planar sensor devices in thick film configuration depositing In2O3–SnO2 nanocrystals by screen-printing. CO and C2H5OH have been tested as gas target. The results obtained are discussed in relation to the chemical and microstructural properties of the synthesized In2O3–SnO2 nanocrystals.