A Verwey-type charge-ordering transition in magnetite at 120 K leads to the formation of linear units of three iron ions with one shared electron, called trimerons. The recently-discovered iron pentoxide (Fe4O5) comprising mixed-valent iron cations at octahedral chains, demonstrates another unusual charge-ordering transition at 150 K involving competing formation of iron trimerons and dimerons. Here, we experimentally show that applied pressure can tune the charge-ordering pattern in Fe4O5 and strongly affect the ordering temperature. We report two charge-ordered phases, the first of which may comprise both dimeron and trimeron units, whereas, the second exhibits an overall dimerization involving both the octahedral and trigonal-prismatic chains of iron in the crystal structure. We link the dramatic change in the charge-ordering pattern in the second phase to redistribution of electrons between the octahedral and prismatic iron chains, and propose that the average oxidation state of the iron cations can pre-determine a charge-ordering pattern.

Ovsyannikov, S., Bykov, M., Bykova, E., Glazyrin, K., Manna, R., Tsirlin, A., et al. (2018). Pressure tuning of charge ordering in iron oxide. NATURE COMMUNICATIONS, 9(1) [10.1038/s41467-018-06457-x].

Pressure tuning of charge ordering in iron oxide

Cerantola V;
2018

Abstract

A Verwey-type charge-ordering transition in magnetite at 120 K leads to the formation of linear units of three iron ions with one shared electron, called trimerons. The recently-discovered iron pentoxide (Fe4O5) comprising mixed-valent iron cations at octahedral chains, demonstrates another unusual charge-ordering transition at 150 K involving competing formation of iron trimerons and dimerons. Here, we experimentally show that applied pressure can tune the charge-ordering pattern in Fe4O5 and strongly affect the ordering temperature. We report two charge-ordered phases, the first of which may comprise both dimeron and trimeron units, whereas, the second exhibits an overall dimerization involving both the octahedral and trigonal-prismatic chains of iron in the crystal structure. We link the dramatic change in the charge-ordering pattern in the second phase to redistribution of electrons between the octahedral and prismatic iron chains, and propose that the average oxidation state of the iron cations can pre-determine a charge-ordering pattern.
Articolo in rivista - Articolo scientifico
Mössbauer spectroscopy; diamond anvil cell; low temperature; high pressure; XRD; iron oxides
English
Ovsyannikov, S., Bykov, M., Bykova, E., Glazyrin, K., Manna, R., Tsirlin, A., et al. (2018). Pressure tuning of charge ordering in iron oxide. NATURE COMMUNICATIONS, 9(1) [10.1038/s41467-018-06457-x].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/397737
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