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M. Schroeder, Manfred Martin

Cation Tracer Diffusion and Electrotransport in Semiconducting Cobaltous Oxide Co_1-δO

The electrotransport and diffusion of host and solute tracer cations in Co_1-δ O was investigated using radioactive isotopes in different experimental arrangements. The results indicate strong flux coupling between the ionic and electronic charge carriers. In consequence, the phenomenological description of these fluxes has to take account of non-negligible cross coefficients L_ik in the transport coefficient matrix, resulting in effective charges of the ions which deviate from their respective formal charges. In the case of cobalt ions, all coefficients of the transport coefficient matrix for Co_1-δ O were determined simultaneously from a single experiment. An effective charge close to +1 was determined for the divalent cobalt ions. In contrast, only an apparent effective charge is obtainable for solute tracer ions. In the case of indium tracer ions, this charge shows a change of sign as a function of oxygen activity. The experimentally observed flux couplings are discussed on the basis of interactions of the mobile point defects in Co_1-δO.

Zeitschrift für Physikalische Chemie, Oldenbourg Wissenschaftsverlag

Print ISSN: 0942-9352
Volume: 207, 01/1998
Pages: 001

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