Pressure tuning of charge ordering in iron oxide

• DOI: 10.1038/s41467-018-06457-x
• Publication Date: 2018-10-02T13:54:31Z
• Authors: Sergey V. Ovsyann...; Maxim Bykov; Elena Bykova; Konstantin Glazyrin; Rudra Sekhar Manna; Alexander A. Tsirlin; Valerio Cerantola; Ilya Kupenko; Alexander V. Kurn...; Innokenty Kantor; Anna S. Pakhomova; Irina Chuvashova; Aleksandr I. Chum...; Rudolf Rüffer; Catherine McCammon; Leonid S. Dubrovi...
• Keywords: VERWEY TRANSITION; PEROVSKITE; [SDV]Life Sciences [q-bio]; Science; ddc:530; Q; LOWER-MANTLE; 500; Article; SINGLE-CRYSTAL; COMPRESSIBILITY; BEAMLINE; Mössbauer spectroscopy; diamond anvil cell; low temperature; high pressure; XRD; iron oxides; CRYSTAL-STRUCTURE; FE4O5; STRUCTURAL BEHAVIOR; MAGNETITE FE3O4; info:eu-repo/classification/ddc/500

AbstractA 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.