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The following gas concentration cell was constructed and the electromotive force was measured, ( ref .,−) Pt ,p H 2 ′,p O 2 ′| α - Al 2 O 3 |p H 2 ″,p O 2 ″, Pt (+, work .) When a difference in oxygen partial pressures was applied to the above cell while maintaining the hydrogen partial pressure on both electrodes at the same value, no significant electromotive force was observed in the experimental temperature range (1273–1673 K). On the application of a difference in hydrogen partial pressures while maintaining both oxygen partial pressures constant, the electromotive force was not observed at high oxygen partial pressure conditions. At low oxygen partial pressure conditions, however, a stable electromotive force depending on the difference in hydrogen partial pressures was clearly observed. The relation between the electromotive force and the hydrogen partial pressures is represented by the following Schmalzried-type equation, E=− RT F ln p″ H 2 1/2 +A p′ H 2 1/2 +A where A is a parameter which depends only on the temperature. In this study, it was clarified that α-Al 2 O 3 could be used as a solid electrolyte for a galvanic cell-type hydrogen sensor at elevated temperature. |
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