Application of a Mixed Oxide Capacitor to the Selective Carbon Dioxide Sensor: II . Sensing Characteristics of a Oxide Capacitor

Abstract

Characteristics for CO2 sensing of a CuO-based oxide capacitor were studied. The capacitances of CuO mixed with BaSnO3, SrTiO~, CaTiO3, and ZnO are dependent on the CO2 concentration, similar to CuO-BaTiO2. In particular, the mixed oxide, CuO-SrTiO3, is more sensitive to CO2 than CuO-BaTiO3, but requires a rather long time to recover. On the other hand, the mixed oxide capacitor, CuO-BaSnO3, exhibits high CO2 sensitivity, and a monotonic and approximately logarithmic relationship exists between the sensitivity and the concentration of CO2 from 100 ppm to 50%. Furthermore, the capacitance of CuO-BaSnO3 increased rapidly within 30 s after exposure to 2% CO2, and returned rapidly to the original level after reexposure to air. Therefore, the system, CuO-BaSnQ is promising for sensing COz over a wide range of concentrations. From a complex impedance measurement, the equivalent circuit of the sensor element can be expressed by a series connection of three parallel resistors and capacitors which correspond to the intragrain region, grain interface between CuO and BaSnO~, and electrode interface. Since exposure of the element to 2% CO2 varied the capacitance of the grain interface, the grain interface between CuO and BaSnO3 has an important role for CO2 detection.

Correlation of microstructure and electrical conduction behaviour with defect structure of niobium doped barium stannate

“…Barium stannate ceramic [2] and barium stannate thin films [3,4] are found to be suitable for use in semiconductor gas sensor devices at elevated temperatures. CuO-BaSnO 3 exhibits high CO 2 sensitivity [5]. Synthesis and electrical properties of the system BaSnO 3 have extensively been studied in our group [6,7].…”

Synthesis and Structural Investigations of Ag‐Added BaTiO3‐CuO Mixed Oxide for CO2 Gas Sensing

“…With respect to the undoped sample, no diffraction peaks except for those from BaTiO 3 and CuO were observed and no changes in the diffraction angles nor in the relative intensities of each diffraction peaks due to BaTiO 3 and CuO can be recognized [8,9]. This means that no solid reaction took place between BaTiO 3 and CuO during the sintering process at 500 and 700…”

Carbon dioxide gas sensing behavior of nanostructured GdCoO3 prepared by a solution-polymerization method

“…According to Ishihara et al, the formation of a thin carbonation layer on the surface of CuO-BaTiO 3 and CuO-SrTiO 3 sensors can be involved in the detection of this gas [33]. However, for other oxide perovskites little information is available about this topic.…”