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Zawodzki M, Weissitsch L, Krenn H, Wurster S, Bachmaier A. Exchange Bias Demonstrated in Bulk Nanocomposites Processed by High-Pressure Torsion. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:344. [PMID: 36678097 PMCID: PMC9861669 DOI: 10.3390/nano13020344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/05/2023] [Accepted: 01/11/2023] [Indexed: 06/17/2023]
Abstract
Ferromagnetic (Fe or Fe20Ni80) and antiferromagnetic (NiO) phases were deformed by high-pressure torsion, a severe plastic deformation technique, to manufacture bulk-sized nanocomposites and demonstrate an exchange bias, which has been reported predominantly for bilayer thin films. High-pressure torsion deformation at elevated temperatures proved to be the key to obtaining homogeneous bulk nanocomposites. X-ray diffraction investigations detected nanocrystallinity of the ferromagnetic and antiferromagnetic phases. Furthermore, an additional phase was identified by X-ray diffraction, which formed during deformation at elevated temperatures through the reduction of NiO by Fe. Depending on the initial powder composition of Fe50NiO50 or Fe10Ni40NiO50 the new phase was magnetite or maghemite, respectively. Magnetometry measurements demonstrated an exchange bias in high-pressure torsion-processed bulk nanocomposites. Additionally, the tailoring of magnetic parameters was demonstrated by the application of different strains or post-process annealing. A correlation between the amount of applied strain and exchange bias was found. The increase of exchange bias through applied strain was related to the microstructural refinement of the nanocomposite. The nanocrystalline maghemite was considered to have a crucial impact on the observed changes of exchange bias through applied strain.
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Affiliation(s)
- Michael Zawodzki
- Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences, 8700 Leoben, Austria
| | - Lukas Weissitsch
- Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences, 8700 Leoben, Austria
| | - Heinz Krenn
- Institute of Physics, University of Graz, 8010 Graz, Austria
| | - Stefan Wurster
- Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences, 8700 Leoben, Austria
| | - Andrea Bachmaier
- Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences, 8700 Leoben, Austria
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Rana D, Lachmayr K, Lustig SR. A review of covetics - current understanding and future perspectives. NANOSCALE ADVANCES 2022; 5:11-26. [PMID: 36605798 PMCID: PMC9765602 DOI: 10.1039/d2na00500j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Covetics are a novel class of metal-carbon composites traditionally fabricated in an induction furnace with high power electrical current in the liquid metal-carbon mixture. The electrical current facilitates chemical conversion of carbon feedstock into graphene-metal crystalline structures. We explore the synthesis mechanism and hypothesize that carbon-metal species, rather than purely-carbon ions, are the reactant species driving the covetic reaction. Experimental mechanical and electrical property characterization in aluminum, silver, and copper covetics demonstrates improved tensile, hardness, and conductivity of covetic metals over pure metal controls. The literature proves that significantly improved material properties are possible with homogeneously distributed graphitic carbon in metal. High resolution transmission electron microscopy shows stripe, multidirectional, and alternating carbon-metal plane lattice structure nanocarbon patterns for aluminum, copper, and silver covetics, respectively, as well as high- and low-carbon concentration regions. Covetic Raman spectra and theoretical calculations indicate characteristic graphene signatures and the possibility of aluminum-graphene and silver-graphene bonding. This review consolidates the current literature and provides new avenues for research.
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Affiliation(s)
- Devyesh Rana
- Department of Chemical Engineering, Northeastern University, Lustig Lab 360 Huntington Avenue Boston MA 02115 USA
| | - Kätchen Lachmayr
- Department of Chemical Engineering, Northeastern University, Lustig Lab 360 Huntington Avenue Boston MA 02115 USA
| | - Steven Raymond Lustig
- Department of Chemical Engineering, Northeastern University, Lustig Lab 360 Huntington Avenue Boston MA 02115 USA
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Huang GY, Hu X, Wirth BD. First-principles investigations of hydrogen trapping in Y 2O 3 and the Y 2O 3|bcc Fe interface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:495001. [PMID: 32914760 DOI: 10.1088/1361-648x/abb17e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Based on first-principles calculations, the binding energy of hydrogen atom to Y2O3 and Y2O3|bcc Fe interface (relative to bcc Fe side) with cube-on-cube orientation is at least 0.45 eV, if hydrogen substitutional is considered, or at least 0.26 eV if only hydrogen interstitial is considered. The calculated binding energies do not have a unique fixed value, because they are dependent on the interface structure, the Fermi level of Y2O3 near the interface and the chemical potential of Y/O. Hydrogen substitutional is more stable than hydrogen interstitial near the interface for Fermi level around calculated Schottky barrier height (SBH) at equilibrium. The Y2O3 particle interior can be an effective trapping site for hydrogen. Hydrogen interstitial, hydrogen substitutional and Y/O vacancy have a much lower energy near the interface than within the Y2O3 particle, presumably due to image charge interaction related to their non-zero charge state. For neutral impurities or defects, the energy near interface and that far away from the interface are similar (⩽0.1 eV difference) for a perfect coherent interface. The Y2O3|bcc Fe interface should provide effective trapping sites for hydrogen atoms in oxide dispersion strengthened (ODS) steels.
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Affiliation(s)
- Gui-Yang Huang
- Department of Nuclear Engineering, University of Tennessee, knoxville, Tennessee, United States of America
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Phase Relations in the FeO-Fe3C-Fe3N System at 7.8 GPa and 1350 °C: Implications for Oxidation of Native Iron at 250 km. MINERALS 2020. [DOI: 10.3390/min10110984] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Oxidation of native iron in the mantle at a depth about 250 km and its influence on the stability of main carbon and nitrogen hosts have been reconstructed from the isothermal section of the ternary phase diagram for the FeO-Fe3C-Fe3N system. The results of experiments at 7.8 GPa and 1350 °C show that oxygen increase in the system to > 0.5 wt % provides the stability of FeO and leads to changes in the phase diagram: the Fe3C, L, and Fe3N single-phase fields change to two-phase ones, while the Fe3C + L and Fe3N + L two-phase fields become three-phase. Сarbon in iron carbide (Fe3C, space group Pnma) is slightly below the ideal value and nitrogen is below the EMPA (Electron microprobe analysis) detection limit. Iron nitride (ε-Fe3N, space group P63/mmc) contains up to 2.7 wt % С and 4.4 wt % N in equilibrium with both melt and wüstite but 2.1 wt % С and 5.4 wt % N when equilibrated with wüstite alone. Impurities in wüstite (space group Fmm) are within the EMPA detection limit. The contents of oxygen, carbon, and nitrogen in the metal melt equilibrated with different iron compounds are within 0.5–0.8 wt % O even in FeO-rich samples; 3.8 wt % C and 1.2 wt % N for Fe3C + FeO; and 2.9 wt % C and 3.5 wt % N for Fe3N + FeO. Co-crystallization of Fe3C and Fe3N from the O-bearing metal melt is impossible because the fields of associated C- and N-rich compounds are separated by that of FeO + L. Additional experiments with excess oxygen added to the system show that metal melt, which is the main host of carbon and nitrogen in the metal-saturated (~0.1 wt %) mantle at a depth of ~250 km and a normal heat flux of 40 mW/m2, has the greatest oxygen affinity. Its partial oxidation produces FeO and causes crystallization of iron carbides (Fe3C and Fe7C3) and increases the nitrogen enrichment of the residual melt. Thus, the oxidation of metal melt in the mantle enriched in volatiles may lead to successive crystallization of iron carbides and nitrides. In these conditions, magnetite remains unstable till complete oxidation of iron carbide, iron nitride, and the melt. Iron carbides and nitrides discovered as inclusions in mantle diamonds may result from partial oxidation of metal melt which originally contained relatively low concentrations of carbon and nitrogen.
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Direct reduction of upgraded titania slag by magnesium for making low-oxygen containing titanium alloy hydride powder. POWDER TECHNOL 2020. [DOI: 10.1016/j.powtec.2020.04.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Site-selective doping of ordered charge states in magnetite. Nat Commun 2020; 11:1671. [PMID: 32245968 PMCID: PMC7125154 DOI: 10.1038/s41467-020-15504-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 03/13/2020] [Indexed: 11/24/2022] Open
Abstract
Charge ordering creates a spontaneous array of differently charged ions and is associated with electronic phenomena such as superconductivity, colossal magnetoresistances (CMR), and multiferroicity. Charge orders are usually suppressed by chemical doping and site selective doping of a charge ordered array has not previously been demonstrated. Here we show that selective oxidation of one out of eight distinct Fe2+ sites occurs within the complex Fe2+/Fe3+ ordered structure of 2%-doped magnetite (Fe3O4), while the rest of the charge and orbitally ordered network remains intact. This ‘charge order within a charge order’ is attributed to the relative instability of the trimeron distortion surrounding the selected site. Our discovery suggests that similar complex charge ordered arrays could be used to provide surface sites for selective redox reactions, or for storing information by doping specific sites. Charge ordering in magnetite is an important example of the complex behaviour that emerges in transition metal oxides. Here the authors show that doping causes selective oxidation of one site in the established trimeron pattern, introducing an additional charge-ordered structure.
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Paul T, Zhang L, Biswas S, Loganathan A, Frith MG, Ilavsky J, Kuzmenko I, Puckette J, Kalkan AK, Agarwal A, Harimkar SP. Quantification of Thermal Oxidation in Metallic Glass Powder using Ultra-small Angle X-ray Scattering. Sci Rep 2019; 9:6836. [PMID: 31048720 PMCID: PMC6497630 DOI: 10.1038/s41598-019-43317-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/02/2019] [Indexed: 11/23/2022] Open
Abstract
In this paper, the composition, structure, morphology and kinetics of evolution during isothermal oxidation of Fe48Cr15Mo14Y2C15B6 metallic glass powder in the supercooled region are investigated by an integrated ex-situ and in-situ characterization and modelling approach. Raman and X-ray diffraction spectra established that oxidation yielded a hierarchical structure across decreasing length scales. At larger scale, Fe2O3 grows as a uniform shell over the powder core. This shell, at smaller scale, consists of multiple grains. Ultra-small angle X-ray scattering intensity acquired during isothermal oxidation of the powder over a wide Q-range delineated direct quantification of oxidation behavior. The hierarchical structure was employed to construct a scattering model that was fitted to the measured intensity distributions to estimate the thickness of the oxide shell. The relative gain in mass during oxidation, computed theoretically from this model, relatively underestimated that measured in practice by a thermogravimetric analyzer due to the distribution in sizes of the particles. Overall, this paper presents the first direct quantification of oxidation in metallic glass powder by ultra-small angle X-ray scattering. It establishes novel experimental environments that can potentially unfold new paradigms of research into a wide spectrum of interfacial reactions in powder materials at elevated temperatures.
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Affiliation(s)
- Tanaji Paul
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, 74078, United States
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, United States
| | - Linqi Zhang
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, 74078, United States
| | - Sourabh Biswas
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, 74078, United States
| | - Archana Loganathan
- Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL, 33174, United States
| | - Matthew G Frith
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, United States
| | - Jan Ilavsky
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, United States
| | - Ivan Kuzmenko
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, United States
| | - Jim Puckette
- Boone Pickens School of Geology, Oklahoma State University, Stillwater, OK, 74078, United States
| | - A Kaan Kalkan
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, 74078, United States
| | - Arvind Agarwal
- Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL, 33174, United States
| | - Sandip P Harimkar
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, 74078, United States.
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Wiencke J, Lavelaine H, Panteix PJ, Petitjean C, Rapin C. Electrolysis of iron in a molten oxide electrolyte. J APPL ELECTROCHEM 2018. [DOI: 10.1007/s10800-017-1143-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Judge W, Allanore A, Sadoway D, Azimi G. E-logpO2 diagrams for ironmaking by molten oxide electrolysis. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.07.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Muwanguzi AJB, Karasev AV, Byaruhanga JK, Jönsson PG. Characterization of Chemical Composition and Microstructure of Natural Iron Ore from Muko Deposits. ACTA ACUST UNITED AC 2012. [DOI: 10.5402/2012/174803] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The study aimed at investigating the chemical composition and microstructure of raw iron ore from the deposits in Muko area (south-western Uganda). The quality of this iron ore was evaluated to establish its suitability to serve as a raw material for iron production. Samples were taken from the six hills of Muko ore deposits and tests carried out to establish their composition and properties. X-ray diffraction and scanning electron microscopy were employed in the investigation and chemical analysis performed to determine the compounds constituting the ore. The quality of this ore was compared to generalized world market standards and ores from other nations. It was found that Muko ore is a rich hematite grade with Fe content above 65%. It has little gangue (<6% SiO2 and 3-4% Al2O3) and low contents of the deleterious elements (P~0.02% and S<0.006%), which correspond to acceptable levels for commercial iron ores.
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Affiliation(s)
- Abraham J. B. Muwanguzi
- Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden
- Department of Mechanical Engineering, School of Engineering, College of Engineering Design Art and Technology, Makerere University, P.O. Box 7062, Kampala, Uganda
| | - Andrey V. Karasev
- Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden
| | - Joseph K. Byaruhanga
- Department of Mechanical Engineering, School of Engineering, College of Engineering Design Art and Technology, Makerere University, P.O. Box 7062, Kampala, Uganda
| | - Pär G. Jönsson
- Department of Material Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden
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Abstract
Phases of the iron-oxygen binary system are significant to most scientific disciplines, directly affecting planetary evolution, life, and technology. Iron oxides have unique electronic properties and strongly interact with the environment, particularly through redox reactions. The iron-oxygen phase diagram therefore has been among the most thoroughly investigated, yet it still holds striking findings. Here, we report the discovery of an iron oxide with formula Fe(4)O(5), synthesized at high pressure and temperature. The previously undescribed phase, stable from 5 to at least 30 GPa, is recoverable to ambient conditions. First-principles calculations confirm that the iron oxide here described is energetically more stable than FeO + Fe(3)O(4) at pressure greater than 10 GPa. The calculated lattice constants, equation of states, and atomic coordinates are in excellent agreement with experimental data, confirming the synthesis of Fe(4)O(5). Given the conditions of stability and its composition, Fe(4)O(5) is a plausible accessory mineral of the Earth's upper mantle. The phase has strong ferrimagnetic character comparable to magnetite. The ability to synthesize the material at accessible conditions and recover it at ambient conditions, along with its physical properties, suggests a potential interest in Fe(4)O(5) for technological applications.
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Investigation of wüstite (Fe1−xO) by femtosecond laser assisted atom probe tomography. Ultramicroscopy 2011; 111:584-8. [DOI: 10.1016/j.ultramic.2010.11.023] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Revised: 11/05/2010] [Accepted: 11/14/2010] [Indexed: 11/16/2022]
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Almjashev VI, Barrachin M, Bechta SV, Bottomley D, Vitol SA, Gusarov VV, Defoort F, Krushinov EV, Lopukh DB, Lysenko AV, Martynov AP, Mezentseva LP, Miassoedov A, Petrov YB, Fischer M, Khabensky VB, Hellmann S. Ternary eutectics in the systems FeO-UO2-ZrO2 and Fe2O3-U3O8-ZrO2. RADIOCHEMISTRY 2011. [DOI: 10.1134/s1066362211010024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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