Application of Mixed Oxide Capacitor to the Selective Carbon Dioxide Sensor: I . Measurement of Carbon Dioxide Sensing Characteristics

Oxide capacitors consisting of and an oxide are studied as a sensor for detection. Although the capacitance change of on exposure to was small, it was greatly enhanced by the combination with . Sensitivity to and optimum operating temperature were strongly dependent on the oxide combined with . The element which contains basic oxides such as and , is highly sensitive to , but the operating temperature exceeded 1073 K. Among the elements investigated in this study, exhibited the highest sensitivity to . selectively responded to , and this element could distinguish the concentrations up to 6%. On the other hand, the capacitance of decreased linearly with increasing concentration up to 20%. Mixed oxide capacitors of and , therefore, are suitable for sensing at the concentration range of hundreds of ppm, and at a percentage level, respectively.