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This paper deals with an impedancemetric sensor based on an yttria-stabilized zirconia (YSZ) using an oxide sensing-electrode (SE) for measuring O 2 concentration. Fourteen oxides were examined as the SE materials for selective detection of O 2 . Among the sensors examined, the YSZ-based sensor using BaFeO 3 -SE was found to be insensitive to interfering gases such as NH 3 , H 2 , C 3 H 6 , C 3 H 8 , CH 4 , NO 2 , NO or CO, while sensitive to only O 2 at 600 °C. The impedance value |Z| at 10 Hz for the sensor using BaFeO 3 -SE decreased linearly with increasing O 2 concentration on a logarithmic scale in the range of 0.05–21 vol.%. The present sensor exhibited quick and repeatable responses to the change in O 2 concentration. [ABSTRACT FROM AUTHOR]

An yttria-stabilized zirconia (YSZ)-based sensor using Zn–Ta-based oxide as a sensing electrode (SE) has been previously reported to generate a highly sensitive and selective response to hydrogen (H 2 ) after the aging of 40 days at 500 °C. This study is focused on shortening such a long aging time (stabilization) for obtaining the high-performance of the sensor. Initially, different heat treatments (changing the sintering parameter and the aging temperature) were done and could not give satisfactory results. However, when the sensor was exposed to 400 ppm H 2 in N 2 (the H 2 treatment), the stabilization time was found to decrease from 40 to 24 days. Prolongation of the H 2 -treatment time from 30 to 60 min helped the sensor using Zn–Ta–O-SE to reach the stabilized level in 15 days. Extending the treatment time up to 120 min gave an adverse effect to the shortening of stabilization time. Furthermore, the sensing performance of the stabilized sensor received the 400 ppm H 2 treatment for 60 min was unaffected by this H 2 treatment, since the sensor was still able to exhibit likewise highly sensitive and selective response to H 2 after the stabilized state was achieved. [ABSTRACT FROM AUTHOR]