Abstract: The Pt, air/YSZ electrode resistance was determined for oxygen sensor with dc polarization of two electrode in the temperature range of 380～800℃.
The (ZrO₂)_0.93(Y₂O₃)_0.07 bulk resistances were obtained from the extrapolation method by ac low frequency impedance measurement, and the electrolyte
dc polarization resistance can be separated from electrode overpotentials. Results show the η-I curves obey the Butler-Volmer equation, with charge transfer
coefficients of two for the Pt, air |YSZ| air, Pt cell. The temperature dependence of the YSZ bulk resistance and the Pt, air/YSZ electrode resistance is
similar and a change in the activation energy of resistance occurs near 600℃ and 570℃ respectively. The exchange current I₀ of electrode as a
funclion of temperature was also measured. At temperature above 700℃, response time of the oxygen sensor is less than 2.5s.

Key words: Pt/YSZ electrode resistance, ZrO₂ oxygen sensor, yttria stabilized zirconia, oxide solid electrolyte