Gas sensing response of nanostructured CoSb$_{2}$O$_{6}$ prepared by non-aqueous solution methods*

Nanostructured CoSb$_{2}$O$_{6}$, with trirutile type structure, was prepared by a non-aqueous solution-polymerization method, using antimony chloride, cobalt nitrate, polyvinyl pyrrolidone and ethyl alcohol. The evaporation, by microwave radiation, of the precipitate obtained in the initial stage of the synthesis, produced an amorphous solid precursor. Further calcination at 700$^{\circ}$C yielded the target composition. X-ray powder diffraction was used to identify the crystal structure, which corresponds to tetragonal with cell parameters a = 4.6544 {\AA} and c = 9.2823 {\AA}, and space group P42/nmn. SEM and TEM were used to analyze particle size and shape; by TEM, nanostructured particles with shape of filaments with 20 nm diameter and length up to 600 nm were observed. Their local crystallinity was confirmed by selected area electron diffraction. To test CoSb$_{2}$O$_{6}$ as a gas sensor material, the powder was deposited on alumina substrates using the screen-printing technique. DC electrical characterization was performed in air, O$_{2}$ and CO$_{2}$ from room temperature to 600$^{\circ}$C. The dynamic response of resistance characterization displayed a variation of about 1k$\Omega$ when detecting CO$_{2}$; whereas for O$_{2}$ a change in the order of 10$^{2} \Omega$ was measured.