Impedancemetric acetylene gas sensing properties of Sm-Fe-based perovskite-type oxide-based thick-film device

摘要

Perovskite-type Sm_(1-x)Ca_xFeO_3 (x=0, 0.05, 0.20, 0.50, 0.75,1.0) powders as sensor materials were prepared by a wet-chemical route using a polymer precursor method at 750 ℃. A perovskite-type oxide thick-film device prepared by a screen-printing method was used for an acetylene (C_2H_2) sensor for which outputs were measured by AC impedance spectroscopy at 400 C. Although sensitivities of the devices using oxides with Ca~(2+) substitution were decreased because of reduction in the amount of impedance change between air and sample gas, the device without Ca~(2+) substitution showed extremely high response at a low frequency. According to Nyquist's plots of the SmFeO_3 device, this is attributed to the fact that impedance of charge transfer from the surface reaction was taken at a low frequency. It was also found that the sensor devices showed good selectivity to interference gases.