Gas sensing response of nanostructured trirutile-type CoSb2O6 synthesized by solution-polymerization method

Nanostructured CoSb2O6 with trirutile-type structure was prepared by a solution-polymerization method using polyvinyl alcohol and sucrose. In this synthesis route, the thermal decomposition of the precursor powder at 700 °C produced well-crystallized CoSb2O6. To obtain the precursor material, microwave radiation was applied during the evaporation of the solution. From X-ray powder diffraction, the tetragonal structure with lattice parameters a = 4.6544 Å and c = 9.2823 Å and space group P42/nmn was calculated. Using scanning electron microscopy at low magnification, the calcined powder exhibited two different morphologies, corresponding to laminas and wires, where the latter is more abundant. Transmission electron microscopy images revealed that the two microstructures were formed by the agglomeration of nanoparticles with an average particle size of 50 nm; their crystallinity was confirmed by selected area electron diffraction. The dynamic response of resistance tests performed in air, O2 and CO2 revealed that CoSb2O6 thick films had high reproducibility in the detection of these gases. However, in CO2 a better performance was observed, based on a uniform response when air and CO2 were alternatively supplied; besides, the variation in resistance under this gas fairly reached two orders of magnitude. From the results obtained in this work, nanostructured CoSb2O6 may be considered as a possible CO2 sensor material.