Effect of the frequency on the gas sensing response of CoSb2O6 prepared by a colloidal method

CoSb(2)O(6) With trirutile-type structure was prepared by a colloidal method using cobalt nitrate hydrate, antimony trichloride, ethylenediamine and ethyl alcohol. To obtain a precursor material, microwave radiation was applied during the evaporation process. The thermal decomposition of the precursor powder at 600 degrees C produced single-phase polycrystalline CoSb(2)O(6). By scanning electron microscopy a widespread formation of microcolumns, having a length in the range of 6-18 mu m, and an average diameter of 2.5 mu m were observed. The gas sensing properties of CoSb(2)O(6) thick films was evaluated by measuring the transient response of the magnitude of the impedance (vertical bar Z vertical bar) in air,CO(2) and O(2). This characterization was made at 100 Hz, 1 kHz and 100 kHz (400 degrees C). The results indicated that increasing the frequency, smaller vertical bar Z vertical bar values were registered. However, a lot more uniform and noise-free response during the detection of these gases was obtained. Polarization curves demonstrated that CoSb(2)O(6) responds quantitatively to changes in the CO(2) concentration. However, in O(2) this behavior was not observed. (C) 2009 Elsevier B.V. All rights reserved.