Experimental evidence of the interference between ionic and electronic flows in an oxide with prevailing electronic conduction

Abstract

Linear transport theory prescribes that for, e.g. a binary oxide Co 1− δ O, a flow of cations ( J 1) may be induced not only by its direct cause which is a gradient of the cationic electrochemical potential (▿η 1), but also indirectly by a gradient of the electronic electrochemical potential (▿η 2), or J 1=− L 11▿ η 1− L 12▿ η 2, L ik being the transport coefficient. Routine practice, however, has been neglecting the cross coefficient, i.e. L 12=0. We have determined experimentally the charge of transport of the cation α ∗ 1 (≡ L 12 L 11 ) for Co 1-δO with three different and independent techniques, and concluded that the cross coefficient is not negligible by any means. All the numerical data on α ∗ 1 up to date are compiled. Consequences of the non-zero cross coefficient and the physico-chemical nature of the charge of transport are discussed.