Effects of transition metal additives on redox stability and high-temperature electrical conductivity of (Fe,Mg)(3)O-4 spinels
authors Ferreira, NM; Kovalevsky, AV; Naumovich, EN; Yaremchenko, AA; Zakharchuk, KV; Costa, FM; Frade, JR
nationality International
journal JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
author keywords Electrical conductivity; Thermal expansion; Spinel; Redox stability; Magnetite
keywords THERMODYNAMIC PROPERTIES; CATION DISTRIBUTIONS; CRYSTAL-STRUCTURES; POINT-DEFECTS; FE-2+ IONS; OXIDES; SIMULATION; MAGNETITE; DIFFRACTION; THERMOPOWER
abstract Magnetite-based spinels are considered as promising oxide materials to meet the requirements for ceramic consumable anodes in molten oxide pyroelectrolysis process, a breakthrough low-CO2 steel technology aimed to overcome the environmental impact of classical extractive metallurgy. The present work focuses on- the assessment of phase relationships, redox stability and electrical conductivity of Fe2.6Me0.2Mg0.2O4 (M = Ni, Cr, Al, Mn, Ti) spinel-type materials at 300-1773 K and p(O-2) from 10(-5) to 0.21 atm. The oxidation state of substituting transition metal cation, affecting the fraction of Fe2+ in spinel lattice, was found to be a key factor, which determines the electronic transport and tolerance against oxidative decomposition, while the impact of preferred coordination of additives on these properties was less pronounced. At T > 650 K thermal expansion of Fe2.6Me0.2Mg0.2O4 ceramics exhibited complex behaviour, and, in highly oxidizing conditions, resulted in significant volume changes, unfavourable for high-temperature electrochemical applications. (C) 2014 Elsevier Ltd. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0955-2219
year published 2014
volume 34
issue 10
beginning page 2339
ending page 2350
digital object identifier (doi) 10.1016/j.jeurceramsoc.2014.02.016
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000336352500022

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