Measurements of electronic and ionic partial conductivities in mixed conductors, without the use of blocking electrodes

Abstract

A novel method for determining partial conductivities in a mixed ionic-electronic conductor (MIEC) is presented. In analogy to the Hebb-Wagner method the contribution from either electrons/holes or ions is eliminated but without the use of blocking electrodes. This is accomplished enforcing a “zero driving force” on the component of interest. To measure the ionic partial conductivity one simply short circuits the MIEC while maintaining the specimen under a chemical activity gradient imposed by the electrodes. This method possesses several advantages over the traditional one which uses blocking electrodes. It is experimentally simpler, enables the determination of lower ionic conductivities and does not require gas tightness of the MIEC. On the other hand the traditional Hebb-Wagner method is more convenient for determining the electronic partial conductivity. However the latter method can be used only if inert blocking electrodes are available. When this is not the case, the new method becomes the optimum one.