Complete representation of isothermal mass and charge transport properties of mixed ionic-electronic conductor La(2)NiO(4+δ).

A variety of electrochemical applications of mixed ionic-electronic conductor compounds hinge on their variety of mass and charge transport properties, e.g., ionic conductivity, electronic conductivity, conductivity with suppressed transfer of either electrons or ions, chemical diffusivity, and permeability. All these transport properties of a compound may be represented completely by an Onsager transport coefficient matrix. Here we introduce a simple electrochemical method to measure all the Onsager coefficients for a mixed conductor oxide with known nonstoichiometry (δ), apply it to construct the Onsager matrix for the system of La(2)NiO(4+δ), and derive thereby its transport properties to compare with the literature values available.