Microstructural and microanalytical examinations of partially reduced doped wustites

Kusiński, J.; Jasieńska, S.; Monty, C.

doi:10.1016/0167-2738(94)90176-7

Cited by 6 publications

(2 citation statements)

References 9 publications

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“…Furthermore, it has been shown elsewhere that these structures can be intergrown with rock-salt structures; e.g. CaFe 5 O 7 , can form as intergrowths in FeO (Kusinski et al, 1994). This can allow extension of this homologous series, of which both Fe 4 O 5 and the possible Fe 5 O 6 are members, to exist as part of a wider compositional assemblage.…”

Section: Discussionmentioning

confidence: 99%

Synthesis and recovery of bulk Fe₄O₅ from magnetite, Fe₃O₄. A member of a self-similar series of structures for the lower mantle and transition zone

Guignard

Crichton

2014

Mineral. mag.

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A multi-anvil press was combined with monochromatic synchrotron X-ray radiation to investigate the synthesis, at high-pressure high-temperature conditions, of a recoverable bulk sample of Fe4O5, from an initial magnetite, Fe3O4, sample. Angle-dispersive diffraction patterns show that magnetite firstly breaks down, into an assemblage of hematite (Fe2O3) + Fe4O5. By increasing temperature at constant load, hematite disappears progressively by either reduction or by melting, or a combination of both. In the final product only Fe4O5 remains and, in the absence of hematite, can be kept stable and be recovered at ambient conditions. Refinement of the diffraction patterns at standard conditions demonstrate that Fe4O5 has the Sr2Tl2O5-type-structure with space group Cmcm and a = 2.8964(2) Å, b = 9.8225(6) Åand c = 12.5808(7) Å. This structure-type and related members of a homologous series, offer the possibility that the general sequence of AB(2+n)X(4+n) chemistries could, under certain conditions, be extended to accommodate prevalent oxygen fugacity or, indeed, other ordered stoichiometries through extension of the c axis by the addition of FeO6 octahedral blocks. This structural series, as in other systems, offers possibilities of hosting charge-transfer, Jahn-Teller and other electronic phenomena − as well as supporting metric distortions. Each of these possibilities is highlighted through illustration and extension to related structure-types, most notably from those of the spinels, post-spinels and post-perovskites.

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Section: Discussionmentioning

confidence: 99%

Synthesis and recovery of bulk Fe₄O₅ from magnetite, Fe₃O₄. A member of a self-similar series of structures for the lower mantle and transition zone

Guignard

Crichton

2014

Mineral. mag.

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“…One other aspect of the topotactic relationships is that the CaIrO 3 type forms part of a homologous series of structure types that includes spinels, postspinels and oxides (Goutenoire et al, 1995;Berastegui et al, 2004;Guignard and Crichton, 2014) and these have been demonstrated to be capable of forming intergrowths with other members of the series, and with rocksalt structures (Kusinsky et al, 1994). The importance of such an assemblage is obvious given that (Mg,Fe) 2 SiO 4 will decompose towards pv + rocksalt prior to the transition to ppv.…”

Section: Discussionmentioning

confidence: 99%

Observation of Sb₂S₃-type post-post-perovskite in NaFeF₃. Implications for ABX₃ and A₂X₃ systems at ultrahigh pressure

et al. 2016

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We describe the structures and transformations that lead to the crystallization of a post-post-perovskite of Sb2S3 type in a GdFeO3-type fluoroperovskite system at high-pressure conditions, through use of large-volume powder and single-crystal x-ray diffraction techniques. The results of this analysis gives unique access to the relative crystallographic orientations of all the polymorphs encountered (GdFeO3 type, CaIrO3 type and Sb2S3 type). We use this information to extend this description to include other calculated and observed forms that are competitive in ABX3 and A2X3 stoichiometries (e.g. α-Gd2S3 and Be3N2 types) and provide substantial information on inter-relationships between these structures. Such information is critical to the interpretation of transition mechanisms, predicting transition sequences and to the expression of directional properties in those transformed structures. The transformation from CaIrO3 type to Sb2S3 type is group-subgroup, from Cmcm with fc2a, to Pnma c5, with no observable volume change, but considerable change to the morphology of the lattice. There is a concomitant increase in coordination and average bond length compared to the post-perovskite form of NaFeF3.

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Crucial Mechanism to the Eutectoid Transformation of Wüstite Scale on Low Carbon Steel

Lin

Huang

et al. 2017

steel research int.

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It is important to realize the transformation behavior of wüstite, because it greatly affects the final structure of the oxide layer and the surface quality of steel products. In the present study, the transformation behaviors of the wüstite layer are examined under nearly‐oxygen‐free conditions in order to simulate the cooling processes after the hot rolled strip is coiled. As the single phase wüstite is prepared at 950 °C, the 460 °C transformed oxide layer is composed of a mixture of iron and magnetite formed through eutectoid reactions. For the 750 °C‐fabricated wüstite, only magnetite is observed after transformation, without iron precipitates, and residual wüstite. It is speculated that the unusual transformation behavior of the low‐temperature‐made wüstite results from the pseudo‐structural intermediate phase transformation between wüstite and magnetite. This pseudo‐structure is a pre‐transformed wüstite and contains various concentrations of ferrous ion, which is determined by the fabrication conditions. During the hot strip mill process, wüstite is produced continuously from finish mill to laminar flow sections and culminated at 570 °C. Consequently, the final eutectoid transformation below 570 °C is dominantly controlled by the surface temperature ranging from 750 to 950 °C for low carbon steel.

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Microstructural and microanalytical examinations of partially reduced doped wustites

Cited by 6 publications

References 9 publications

Synthesis and recovery of bulk Fe₄O₅ from magnetite, Fe₃O₄. A member of a self-similar series of structures for the lower mantle and transition zone

Synthesis and recovery of bulk Fe₄O₅ from magnetite, Fe₃O₄. A member of a self-similar series of structures for the lower mantle and transition zone

Observation of Sb₂S₃-type post-post-perovskite in NaFeF₃. Implications for ABX₃ and A₂X₃ systems at ultrahigh pressure

Crucial Mechanism to the Eutectoid Transformation of Wüstite Scale on Low Carbon Steel

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Microstructural and microanalytical examinations of partially reduced doped wustites

Cited by 6 publications

References 9 publications

Synthesis and recovery of bulk Fe4O5 from magnetite, Fe3O4. A member of a self-similar series of structures for the lower mantle and transition zone

Synthesis and recovery of bulk Fe4O5 from magnetite, Fe3O4. A member of a self-similar series of structures for the lower mantle and transition zone

Observation of Sb2S3-type post-post-perovskite in NaFeF3. Implications for ABX3 and A2X3 systems at ultrahigh pressure

Crucial Mechanism to the Eutectoid Transformation of Wüstite Scale on Low Carbon Steel

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Synthesis and recovery of bulk Fe₄O₅ from magnetite, Fe₃O₄. A member of a self-similar series of structures for the lower mantle and transition zone

Synthesis and recovery of bulk Fe₄O₅ from magnetite, Fe₃O₄. A member of a self-similar series of structures for the lower mantle and transition zone

Observation of Sb₂S₃-type post-post-perovskite in NaFeF₃. Implications for ABX₃ and A₂X₃ systems at ultrahigh pressure