Reassessment of conventional polarization technique to measure partial electronic conductivity of electrolytes

Abstract

Two-probe Hebb-Wagner polarization technique has been widely used to determine the partial electronic conductivity of an ionic conductor. The crucial, but often ignored pre-requisite with this technique is that the electronic over-potential at the electrodes be small enough to be neglected. In our own earlier experiences, however, this pre-requisite is not always true. In this study, we constructed a noble, 4-probe polarization cell, which allows measuring the true partial electronic conductivity without any electrode over-potential problem. We applied this new technique to 10 m/o Gd-doped CeO2 (GDC) and compared the results with those from the conventional 2-probe technique. According to the comparison, electronic conductivity of GDC from 2-probe technique is always underestimated by 2-3 times while the 4-probe technique has turned out to be in perfect agreement with the estimated value from the total conductivity in its exclusively n-type regime. In this study we will report the experimental details of this noble 4-probe polarization technique as well as its viability in partial conductivity measurement. (C) 2010 Elsevier B.V. All rights reserved.