Textural, structural and electrical properties of SnO2 nanoparticles prepared by the polyol method

Nanocrystalline mesoporous SnO2 nanoparticles were synthesized by the polyol method followed by thermal annealing. The composition, texture, structure and morphology of the samples treated at 90, 500 and 700 degrees C in air were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR), thermogravimetry coupled to mass spectrometry (DTA/TGA/MS) and Nitrogen Sorption Porosimetry. FTIR and TGA-MS data indicate that tin oxide species were obtained with a complete removal of polyol residues after thermal treatment above 500 degrees C. XRD patterns reveal that nanocrystallites of cassiterite, i. e. rutile-like tetragonal structure, SnO2 were formed after annealing, the average crystallite size increasing with the temperature of the thermal post-treatment. Moreover, TEM and N-2 sorption porosimetry show that the calcined samples are composed of an aggregated network of almost spherical nanoparticles, the mesoporosity observed being related to the interparticle space. Finally, electrical properties of the SnO2 nanopowder calcined at 700 degrees C were studied between 543 and 723 K, in the 200 Hz-5 MHz frequency range by impedance measurements. Bulk conductivity dependence with temperature was found to follow an Arrhenius law with an activation energy of 0.68 eV that is typical of tin dioxide nanopowders.