Mise en évidence de CaF2e4O6 et détermination des structures cristallines des ferrites de calcium CaFe2+nO4+n(n = 1, 2, 3): nouvel exemple d'intercroissance

Evrard, O.; Malaman, B.; Jeannot, F.; Courtois, A.; Alebouyeh, H.; Gerardin, R.

doi:10.1016/0022-4596(80)90471-5

Cited by 50 publications

(47 citation statements)

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“…Here, following recent studies of spin and charge ordering in non-spinel M Fe n –1 O n +1 ( n ≥ 4) ferrites with M = Fe 6,7 , Mn 8,9 and Ca 10,11 , we investigate n = 4 CaFe 3 O 5 and discover long range electronic phase separation between a magnetite-like charge ordered phase and a charge averaged phase.…”

Section: Introductionmentioning

confidence: 99%

Long range electronic phase separation in CaFe3O5

et al. 2018

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Incomplete transformations from ferromagnetic to charge ordered states in manganite perovskites lead to phase-separated microstructures showing colossal magnetoresistances. However, it is unclear whether electronic matter can show spontaneous separation into multiple phases distinct from the high temperature state. Here we show that paramagnetic CaFe3O5 undergoes separation into two phases with different electronic and spin orders below their joint magnetic transition at 302 K. One phase is charge, orbital and trimeron ordered similar to the ground state of magnetite, Fe3O4, while the other has Fe2+/Fe3+charge averaging. Lattice symmetry is unchanged but differing strains from the electronic orders probably drive the phase separation. Complex low symmetry materials like CaFe3O5 where charge can be redistributed between distinct cation sites offer possibilities for the generation and control of electronic phase separated nanostructures.

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Section: Introductionmentioning

confidence: 99%

Long range electronic phase separation in CaFe3O5

et al. 2018

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“…Figure 9 show reaction schemes obtained in situ by Q-XRD for the specimen (a) Fe64Ca36, (b) Fe80Ca20, and (c) Fe90Ca10 when heated from 300 to 1 773 K at a rate of 5.0 × 10 −1 K/s. In the specimen Fe80Ca20, the CF phase started to form at T = 1 443 K. On further heating, CF phases reacted with α-Fe2O3 (F) and the Ca2Fe2O5 (C2F), 12) CaFe2O4 (CF), 13) CaFe4O7 (CF2), 14) and CaFe4O6 (CW2F) 17) (Online version in color). amount of CF2 increased (CaFe2O4 + Fe2O3 → CaFe4O7) at T > 1 453 K, which is 25 K higher than that in the equilibrium state (ΔT1 b = 25 K).…”

Section: Structure Change In the Heating Processmentioning

confidence: 99%

“…CaFe4O7 (CF2) is a high-temperature phase, which is reported to be stable only between 1 428 and 1 499 K. However, other phases containing Fe 2+ were reported to form α−CFF, β− CFF, and γ−CFF depending on oxygen potential, 15) Ca2Fe9O13 (C2W5F2) and Ca2Fe7O11 (C2W3F2) at 1 393 K, 16) and CaFe3O5 (CWF), CaFe4O6 (CW2F), and CaFe5O7 (CW3F). 17) These studies show that the type and amount of coexisting phases are sensitive to the heating condition and chemical composition even nearly at equilibrium state.…”

Section: Introductionmentioning

confidence: 99%

“Continuous Cooling Transformation (CCT)” Concept for Iron Ore Sintering Using In Situ Quick X-ray Diffraction and Confocal Laser Microscope

Kimura

Murao

2013

ISIJ Int.

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In this study, the formation of calcium ferrites during heating and cooling was investigated by in situ and real-time observation using a newly developed system, i.e., "quick X-ray diffraction (Q-XRD)," and an in situ laser microscope. In the new Q-XRD, a specimen was heated up to 1 773 K, and X-ray diffraction patterns were measured using a pixel-array area detector with an interval as short as a few seconds. In situ observation both of crystal structure and microstructure successfully revealed the effects of heating and cooling rates on the sintering reaction in the CaO-Fe2O3 system with special attention to overheating and overcooling phenomena. The first continuous cooling transformation (CCT) concept for iron ore sintering was proposed to understand overcooling phenomena when the molten oxide cooled down to room temperature and magnetite (Fe3O4), hematite (Fe2O3), and various types of calcium ferrite were formed. The CCT diagram for sintering provides crucial and fundamental information on the sintering accompanying solidification, precipitation, and formation of calcium ferrites from the molten oxide, and can be used as a guideline for controlling sintering processes.

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“…The M2 site has a much larger distortion than the M1 site (Table 1 4), since one of the bond lengths (M2-O2b) of the octahedral coordination is much longer than the other five (Evrard et al 1980;Boffa Ballaran et al 2015). Such distortion is retained with increasing pressure due to a very anisotropic compression of the M2-O bonds.…”

Section: Structural Behavior Of Mg 2 Fe 2 O 5 With Pressurementioning

confidence: 93%

Compressibility and high-pressure structural behavior of Mg₂Fe₂O₅

Siersch

Ballaran

Uenver‐Thiele

et al. 2017

American Mineralogist

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The compressibility and structural behavior of the novel Mg 2 Fe 2 O 5 oxide has been investigated by in situ single-crystal X-ray diffraction in a diamond-anvil cell up to a pressure of 17 GPa. The bulk compressibility of Mg 2 Fe 2 O 5 can be described using a second-order Birch-Murnaghan equation of state (BM2 EoS) with V 0 = 352.4(2) Å 3 and K 0 = 171(4) GPa. Three linear BM2 EoS were used to describe the axial compressibility of Mg 2 Fe 2 O 5 , which was found to be highly anisotropic. The a and b lattice parameters have very similar compressibilies, with a 0 = 2.8917(11) Å and linear modulus M a = 572(16) GPa and b 0 = 9.736(3) Å and linear modulus M b = 583(15) GPa, respectively. The c-axis is the most compressible direction as indicated by the smaller linear modulus [c 0 = 12.520(15) Å and M c = 404(28) GPa]. The Mg 2 Fe 2 O 5 structure consists of edge-sharing octahedra alternating with layers of trigonal prisms. The compression behavior of the M-O bonds of the M1 and M2 octahedra and of the M3 prisms depend on their location in either an edge-sharing environment, which makes them stiffer, or a corner-sharing environment where they have more freedom to distort and compress. The main compression mechanism consists of a polyhedral tilting around the M2-O1-M2 angle, which decreases with increasing pressure. Mg 2 Fe 2 O 5 has recently been added to the list of stable end-members of phases with M 4 O 5 stoichiometry, making it a potentially relevant phase in the Earth's upper mantle and transition zone. To develop thermodynamic activity-composition models for high-pressure phases, it is crucial to know the accurate elastic parameters of each individual end-member. Currently these have only been measured for Mg 2 Fe 2 O 5 (this study) and Fe 4 O 5 .

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Mise en évidence de CaF2e4O6 et détermination des structures cristallines des ferrites de calcium CaFe2+nO4+n(n = 1, 2, 3): nouvel exemple d'intercroissance

Cited by 50 publications

References 4 publications

Long range electronic phase separation in CaFe3O5

Long range electronic phase separation in CaFe3O5

“Continuous Cooling Transformation (CCT)” Concept for Iron Ore Sintering Using In Situ Quick X-ray Diffraction and Confocal Laser Microscope

Compressibility and high-pressure structural behavior of Mg₂Fe₂O₅

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Mise en évidence de CaF2e4O6 et détermination des structures cristallines des ferrites de calcium CaFe2+nO4+n(n = 1, 2, 3): nouvel exemple d'intercroissance

Cited by 50 publications

References 4 publications

Long range electronic phase separation in CaFe3O5

Long range electronic phase separation in CaFe3O5

“Continuous Cooling Transformation (CCT)” Concept for Iron Ore Sintering Using In Situ Quick X-ray Diffraction and Confocal Laser Microscope

Compressibility and high-pressure structural behavior of Mg2Fe2O5

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Compressibility and high-pressure structural behavior of Mg₂Fe₂O₅