Guidelines to design multicomponent ferrospinels for high-temperature applications
authors Ferreira, NM; Ferro, MC; Mikhalev, SM; Costa, FM; Frade, JR; Kovalevsky, AV
nationality International
journal RSC ADVANCES
keywords ELECTRICAL-CONDUCTIVITY; SPINEL STRUCTURE; CATION DISTRIBUTION; MAGNETIC-PROPERTIES; REDOX STABILITY; SITE OCCUPANCY; FE-2+ IONS; IRON; NANOPARTICLES; THERMOPOWER
abstract This work explores the possibilities to design magnetite-based spinels through multiple simultaneous co-substitutions with transition metal cations, with emphasis on redox behavior and electronic transport. For the first time this approach was assessed for high-temperature applications, which is of particular interest for the development of consumable anodes for pyroelectrolysis, an alternative carbon-lean steelmaking process. A Taguchi plan was used to assess the impact of the concentration of substituting chromium, titanium, manganese and nickel cations on the lattice parameter and electrical conductivity of the multicomponent ferrospinels. The results revealed a comparable decrease in the electrical conductivity, provided by Cr3+, Mn3+/2+ and Ni2+ cations. The impact of Ti4+ was found to be less negative, contributed by the formation of Fe2+ cations and increased hopping probability. The strongest structural impacts, exerted by manganese cations, are likely to affect the mobility of polarons, as revealed by the analysis of the correlation factors for combined effects. Ferrospinels, containing various transition metal cations, are more susceptible to oxidation and phase decomposition, which often result in a sudden conductivity drop and significant dimensional changes in the ceramics. The observed trends for redox behavior suggest that the potential applications of multicomponent ferrospinels in oxidizing conditions are limited to 1000-1400 K due to insufficient stability, while higher temperature applications, requiring significant electronic conductivity, are rather suitable.
publisher ROYAL SOC CHEMISTRY
issn 2046-2069
year published 2016
volume 6
issue 39
beginning page 32540
ending page 32548
digital object identifier (doi) 10.1039/c6ra03671f
web of science category Chemistry, Multidisciplinary
subject category Chemistry
unique article identifier WOS:000374045900017
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