Electrotransport-induced demixing in semiconducting (Mn xFe 1− x) 3O 4

• Published in: Solid state ionics Vol. 113; pp. 265 - 270
• Main Authors: Hong, Jeong-Oh, Yoo, Han-Ill
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1998
• Subjects: (Mn xFe 1−x) 3O 4; Charge of transport; Demixing; Ferrite; SOFC; Charge of transport; Demixing; Ferrite; (Mn xFe 1−x) 3O 4; SOFC
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/S0167-2738(98)00291-4

Electrotransport-induced demixing has been studied experimentally and theoretically on the system of semiconducting spinel ferrite, (Mn 0.334Fe 0.666) 3O 4 in a constant current condition at P O 2 =10 −6 atm and 1200°C where interstitial defects are prevailing. The degree of unmixing is determined not only by the difference in diffusivity of the cations but also by their effective charge. The latter is, in turn, determined by the cross effect between electronic and ionic flows. It has been found that the charge of transport as a measure of this cross effect is at least α*=1.2∼1.5 for the cations. Their mean effective charge is thus reduced from 8/3 to 8/3− α*, consequently reducing the degree of unmixing by ca. 40% compared to what would otherwise be.