A Appendix 1—Terminal Potential Difference

Let us prove the relations between the voltage drop over the central phase and the difference in the respective electrochemical potentials given in Section 111.3.iii on page 94. First, we consider the symmetrical cell 6 (on page 75) and assume transfer equilibrium for the non blocked charge carrier. The contact metal, Oz/ion conductor is, on the metal-side, indicated with 1 (on the other side of the cell with 8) on the ion conductor side the contact is indicated with 2 and 7, respectively. The ion conductor/sample contact is denoted by 3 and 6 on the ion conductor side, and on the sample-side by 4 and 5. Hence 

If the partial pressures on both sides are the same it finally results because -(zi = and A that 

Owing to jUq2 — const in the ion conductor it follows that 

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