Open circuit voltage (OCV) measurements in H
2O/air concentration cells at T<580 K using Yb-doped SrCeO
3 electrolyte indicate that under these conditions, protons are transported through the electrolyte as -ve ions, possibly as
hydroxyl (OH
−) ions. The H
+ ionic transport, which is generally reported, becomes the dominant mode for H
2O/air concentration cells at temperatures greater than 750 K or when H
2O/air electrodes are replaced by H
2/Ar, and the anomalous OC
V sign disappears. The combination of low temperature and the presence of hydrogen and oxygen as
provided by the H
2O/air system appears to be necessary for the postulated hydroxyl ion electrode reactions to take place.
In addition to OC
V measurements, results from impedance spectroscopy are used to provide evidence in support of the suggested
hydroxyl ion mode of protonic transport under the specified conditions. These findings are directly relevant in the development
of novel humidity sensors in the temperature range 450–580K and is reported in a separate paper in this conference.
Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996
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