An electrochemical cell was described which permitted measurements to be made of the ionic and electronic conductivities of mixed conductors as a function of composition. On one side of a disc-shaped sample were mounted 4 peripheral and roughly equidistant electronic contacts. On the other side, 4 ionic contacts were positioned in the same way. As the cell was based upon the van der Pauw geometry, only the thickness of the sample (and not the spacings between the electronic and ionic contacts) had to be determined. The composition of the sample could then be altered by means of coulometric titration. In the case of conductivity measurements of mixed conductors, the composition gradient of the sample (which arose from the flow of electrons and ions in the mixed conductor) was considered in detail. In order to demonstrate the high stoichiometric resolution, the cell was applied to a study of the composition dependence of the ionic and electronic conductivities of -Ag2Te at 300C.

W.Preis, W.Sitte: Solid State Ionics, 1995, 76[1-2], 5-14