High-temperature conductivity, stability and redox properties of Fe3-xAlxO4 spinel-type materials
authors Kovalevsky, AV; Naumovich, EN; Yaremchenko, AA; Frade, JR
nationality International
journal JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
author keywords Electrical conductivity; Thermal expansion; Spinels; Redox stability
keywords IRON-ALUMINATE SPINELS; FE-AL-O; CATION DISTRIBUTION; SUBSTITUTED MAGNETITES; ELECTRICAL-PROPERTIES; THERMAL-EXPANSION; PHASE; SYSTEM; DECOMPOSITION; THERMOPOWER
abstract Iron-based oxides are considered as promising consumable anode materials for high temperature pyroelectrolysis. Phase relationships, redox stability and electrical conductivity of Fe3-xAlxO4 spinels were studied at 300-1773 K and p(O-2) from 10(-5) to 0.21 atm. Thermogravimetry/XRD analysis revealed metastability of the sintered ceramics at 300-1300 K. Low tolerance against oxidation leads to dimensional changes of ceramics upon thermal cycling. Activation energies of the total conductivity corresponded to the range of 16-26 kJ/mol at 1450-1773 K in Ar atmosphere. At 1573-1773 K and p(O-2) ranging from 10(-5) to 0.03 atm, the total conductivity of Fe3-xAlxO4 is nearly independent of the oxygen partial pressure. The conductivity values of Fe3-xAlxO4 (0.1 <= x <= 0.4) at 1773 K and p(O-2) similar to 10(-5) to 10(-4) atm were found to be only 1.1-1.5 times lower than for Fe3O4, showing high potential of moderate aluminium additions as a strategy for improvement of refractoriness for magnetite without significant deterioration of electronic transport. (c) 2012 Elsevier Ltd. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0955-2219
year published 2012
volume 32
issue 12
beginning page 3255
ending page 3263
digital object identifier (doi) 10.1016/j.jeurceramsoc.2012.04.040
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000306298300028
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