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Alfke JL, Müller A, Clark AH, Cervellino A, Plodinec M, Comas-Vives A, Copéret C, Safonova OV. BCC-Cu nanoparticles: from a transient to a stable allotrope by tuning size and reaction conditions. Phys Chem Chem Phys 2022; 24:24429-24438. [PMID: 36189722 PMCID: PMC9554935 DOI: 10.1039/d2cp03593f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022]
Abstract
Metallic copper generally adopts an FCC structure. In this work, we detect highly unusual BCC-structured Cu nanoparticles as a transient intermediate during the H2 reduction of a CuI precursor, [Cu4OtBu4], grafted onto the surface of partially dehydroxylated silica. The Cu BCC structure, assigned by in situ Cu K-edge XANES and EXAFS, as well as in situ synchrotron PXRD, converts upon heating into the most commonly found FCC allotrope. DFT calculations show that the BCC-Cu phase is in fact predicted to be more stable for small particles, and that their stability increases at lower H2 concentrations. Using this knowledge, we show that it is possible to synthesize BCC-structured Cu nanoparticles as a stable allotrope by reduction of the same grafted precursor either in 10% H2 diluted in Ar or 100% H2 at low temperature.
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Affiliation(s)
- Jan L Alfke
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir Prelog Weg 2, Zurich, Switzerland.
- Paul Scherrer Institute, Forschungsstrasse 111, CH-5232 Villigen, Switzerland
| | - Andreas Müller
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir Prelog Weg 2, Zurich, Switzerland.
| | - Adam H Clark
- Paul Scherrer Institute, Forschungsstrasse 111, CH-5232 Villigen, Switzerland
| | - Antonio Cervellino
- Paul Scherrer Institute, Forschungsstrasse 111, CH-5232 Villigen, Switzerland
| | - Milivoj Plodinec
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir Prelog Weg 2, Zurich, Switzerland.
| | - Aleix Comas-Vives
- Institute of Materials Chemistry, TU Wien, 1060 Vienna, Austria
- Departament de Química, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Catalonia, Spain
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir Prelog Weg 2, Zurich, Switzerland.
| | - Olga V Safonova
- Paul Scherrer Institute, Forschungsstrasse 111, CH-5232 Villigen, Switzerland
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2
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Abstract
Using X-ray emission spectroscopy, we find appreciable local magnetic moments until 30 GPa to 40 GPa in the high-pressure phase of iron; however, no magnetic order is detected with neutron powder diffraction down to 1.8 K, contrary to previous predictions. Our first-principles calculations reveal a "spin-smectic" state lower in energy than previous results. This state forms antiferromagnetic bilayers separated by null spin bilayers, which allows a complete relaxation of the inherent frustration of antiferromagnetism on a hexagonal close-packed lattice. The magnetic bilayers are likely orientationally disordered, owing to the soft interlayer excitations and the near-degeneracy with other smectic phases. This possible lack of long-range correlation agrees with the null results from neutron powder diffraction. An orientationally disordered, spin-smectic state resolves previously perceived contradictions in high-pressure iron and could be integral to explaining its puzzling superconductivity.
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3
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Werellapatha K, Escanhoela CA, Fabbris G, Haskel D, Ankudinov A, Chow P. Evolution of electronic and magnetic properties of nominal magnetite nanoparticles at high pressure probed by x-ray absorption and emission techniques. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:255301. [PMID: 30889564 DOI: 10.1088/1361-648x/ab111d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We present a study of electronic and magnetic properties of nominal magnetite nanoparticles (NPs) (~6 nm) at high pressure in the presence of silicon pressure medium using x-ray absorption near edge structure (XANES), x-ray magnetic circular dichroism (XMCD) and non-resonant x-ray emission spectroscopy (XES). XANES data show a reduction of Fe charge state, a change in local environment around Fe at tetrahedral sites, and a reduced occupation of Fe 4p orbitals, not seen in previous pressure studies of bulk magnetite. XMCD data show a continuous magnetic moment reduction of ~50% between ambient pressure and 20 GPa, similar to what was observed in previous bulk magnetite studies. XES spectra of NPs indicate a gradual change in spin configuration away from the high-spin state consistent with a postulated charge transfer from Fe 4p to 3d states and the observed reduction in XMCD signal. Taken together, the results point to substantial differences in the response of electronic and magnetic properties of the nano-counterparts of bulk magnetite at high pressure.
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Affiliation(s)
- Kalpani Werellapatha
- Department of Physics and Astronomy, University of Maine, Orono, ME 04469, United States of America
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4
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Gorbunov DI, Strohm C, Henriques MS, van der Linden P, Pedersen B, Mushnikov NV, Rosenfeld EV, Petříček V, Mathon O, Wosnitza J, Andreev AV. Microscopic Nature of the First-Order Field-Induced Phase Transition in the Strongly Anisotropic Ferrimagnet HoFe_{5}Al_{7}. PHYSICAL REVIEW LETTERS 2019; 122:127205. [PMID: 30978077 DOI: 10.1103/physrevlett.122.127205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/08/2018] [Indexed: 06/09/2023]
Abstract
We report on x-ray magnetic circular dichroism experiments in pulsed fields up to 30 T to follow the rotations of individual magnetic moments through the field-induced phase transition in the ferrimagnet HoFe_{5}Al_{7}. Near the ground state, we observe simultaneous stepwise rotations of the Ho and Fe moments and explain them using a two-sublattice model for an anisotropic ferrimagnet with weak intersublattice exchange interactions. Near the compensation point, we find two phase transitions. The additional magnetization jump reflects the fact that the Ho moment is no longer rigid as the applied field acts against the intersublattice exchange field.
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Affiliation(s)
- D I Gorbunov
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - C Strohm
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - M S Henriques
- Institut Laue Langevin, 71 Avenue des Martyrs, F-38042 Grenoble, France
- Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic
| | - P van der Linden
- European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble, France
| | - B Pedersen
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - N V Mushnikov
- Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Kovalevskaya 18, 620990 Ekaterinburg, Russia
| | - E V Rosenfeld
- Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Kovalevskaya 18, 620990 Ekaterinburg, Russia
| | - V Petříček
- Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic
| | - O Mathon
- European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble, France
| | - J Wosnitza
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Institut für Festkörperphysik, TU Dresden, D-01062 Dresden, Germany
| | - A V Andreev
- Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic
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5
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Timoshenko J, Anspoks A, Cintins A, Kuzmin A, Purans J, Frenkel AI. Neural Network Approach for Characterizing Structural Transformations by X-Ray Absorption Fine Structure Spectroscopy. PHYSICAL REVIEW LETTERS 2018; 120:225502. [PMID: 29906159 DOI: 10.1103/physrevlett.120.225502] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Indexed: 06/08/2023]
Abstract
The knowledge of the coordination environment around various atomic species in many functional materials provides a key for explaining their properties and working mechanisms. Many structural motifs and their transformations are difficult to detect and quantify in the process of work (operando conditions), due to their local nature, small changes, low dimensionality of the material, and/or extreme conditions. Here we use an artificial neural network approach to extract the information on the local structure and its in situ changes directly from the x-ray absorption fine structure spectra. We illustrate this capability by extracting the radial distribution function (RDF) of atoms in ferritic and austenitic phases of bulk iron across the temperature-induced transition. Integration of RDFs allows us to quantify the changes in the iron coordination and material density, and to observe the transition from a body-centered to a face-centered cubic arrangement of iron atoms. This method is attractive for a broad range of materials and experimental conditions.
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Affiliation(s)
- Janis Timoshenko
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, USA
| | - Andris Anspoks
- Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, Riga, LV-1063, Latvia
| | - Arturs Cintins
- Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, Riga, LV-1063, Latvia
| | - Alexei Kuzmin
- Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, Riga, LV-1063, Latvia
| | - Juris Purans
- Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, Riga, LV-1063, Latvia
| | - Anatoly I Frenkel
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, USA
- Division of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
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6
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Sun X, Sun F, Sun Z, Chen J, Du X, Wang J, Jiang Z, Huang Y. Disorder effects on EXAFS modeling for catalysts working at elevated temperatures. Radiat Phys Chem Oxf Engl 1993 2017. [DOI: 10.1016/j.radphyschem.2016.01.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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7
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High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi. Nat Commun 2017; 8:15634. [PMID: 28541277 PMCID: PMC5458502 DOI: 10.1038/ncomms15634] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/17/2017] [Indexed: 01/12/2023] Open
Abstract
High-entropy alloys, near-equiatomic solid solutions of five or more elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys exhibiting only face- or body-centered cubic structures. Here, we report the high-pressure synthesis of a hexagonal close-packed phase of the prototypical high-entropy alloy CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial fcc structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the transformation is sluggish, occurring over a range of >40 GPa. However, the behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This demonstrates a means of tuning the structures and properties of high-entropy alloys in a manner not achievable by conventional processing techniques. High-entropy alloys represent a new strategy for the design of materials with properties superior to those of conventional alloys, but are largely limited to simple phases of cubic symmetry. By applying high pressures on CrMnFeCoNi, here authors demonstrate synthesis of a hexagonal close-packed phase.
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8
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Surh MP, Benedict LX, Sadigh B. Magnetostructural Transition Kinetics in Shocked Iron. PHYSICAL REVIEW LETTERS 2016; 117:085701. [PMID: 27588867 DOI: 10.1103/physrevlett.117.085701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Indexed: 06/06/2023]
Abstract
A generalized Heisenberg model is implemented to study the effect of thermal magnetic disorder on kinetics of the Fe α-ε transition. The barrier to bulk martensitic displacement remains large in α-Fe shocked well past the phase line but is much reduced in the [001] α-ε boundary. The first result is consistent with observed overdriving to metastable α, while the second suggests structural instability, as implied by observation of a [001] shock transformation front without plastic relaxation. Reconciling both behaviors may require concurrent treatment of magnetic and structural order.
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Affiliation(s)
- Michael P Surh
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Lorin X Benedict
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Babak Sadigh
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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9
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Probing local and electronic structure in Warm Dense Matter: single pulse synchrotron x-ray absorption spectroscopy on shocked Fe. Sci Rep 2016; 6:26402. [PMID: 27246145 PMCID: PMC4887872 DOI: 10.1038/srep26402] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 04/28/2016] [Indexed: 12/02/2022] Open
Abstract
Understanding Warm Dense Matter (WDM), the state of planetary interiors, is a new frontier in scientific research. There exists very little experimental data probing WDM states at the atomic level to test current models and those performed up to now are limited in quality. Here, we report a proof-of-principle experiment that makes microscopic investigations of materials under dynamic compression easily accessible to users and with data quality close to that achievable at ambient. Using a single 100 ps synchrotron x-ray pulse, we have measured, by K-edge absorption spectroscopy, ns-lived equilibrium states of WDM Fe. Structural and electronic changes in Fe are clearly observed for the first time at such extreme conditions. The amplitude of the EXAFS oscillations persists up to 500 GPa and 17000 K, suggesting an enduring local order. Moreover, a discrepancy exists with respect to theoretical calculations in the value of the energy shift of the absorption onset and so this comparison should help to refine the approximations used in models.
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10
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Pascarelli S, Mathon O, Mairs T, Kantor I, Agostini G, Strohm C, Pasternak S, Perrin F, Berruyer G, Chappelet P, Clavel C, Dominguez MC. The Time-resolved and Extreme-conditions XAS (TEXAS) facility at the European Synchrotron Radiation Facility: the energy-dispersive X-ray absorption spectroscopy beamline ID24. JOURNAL OF SYNCHROTRON RADIATION 2016; 23:353-68. [PMID: 26698085 PMCID: PMC5297599 DOI: 10.1107/s160057751501783x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/23/2015] [Indexed: 05/27/2023]
Abstract
The European Synchrotron Radiation Facility has recently made available to the user community a facility totally dedicated to Time-resolved and Extreme-conditions X-ray Absorption Spectroscopy--TEXAS. Based on an upgrade of the former energy-dispersive XAS beamline ID24, it provides a unique experimental tool combining unprecedented brilliance (up to 10(14) photons s(-1) on a 4 µm × 4 µm FWHM spot) and detection speed for a full EXAFS spectrum (100 ps per spectrum). The science mission includes studies of processes down to the nanosecond timescale, and investigations of matter at extreme pressure (500 GPa), temperature (10000 K) and magnetic field (30 T). The core activities of the beamline are centered on new experiments dedicated to the investigation of extreme states of matter that can be maintained only for very short periods of time. Here the infrastructure, optical scheme, detection systems and sample environments used to enable the mission-critical performance are described, and examples of first results on the investigation of the electronic and local structure in melts at pressure and temperature conditions relevant to the Earth's interior and in laser-shocked matter are given.
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Affiliation(s)
- S. Pascarelli
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - O. Mathon
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - T. Mairs
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - I. Kantor
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - G. Agostini
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - C. Strohm
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
- Deutsches Elektronen Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - S. Pasternak
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - F. Perrin
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - G. Berruyer
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - P. Chappelet
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - C. Clavel
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - M. C. Dominguez
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France
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11
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Abstract
Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa.
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12
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Torchio R, Mathon O, Pascarelli S. XAS and XMCD spectroscopies to study matter at high pressure: Probing the correlation between structure and magnetism in the 3d metals. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.02.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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13
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Nucleation and growth mechanisms of hcp domains in compressed iron. Sci Rep 2014; 4:5273. [PMID: 24920496 PMCID: PMC4053698 DOI: 10.1038/srep05273] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 05/23/2014] [Indexed: 11/30/2022] Open
Abstract
In our previous work, we have pointed out that the shock-induced phase transition in iron occurs with the help of interface energy which reduces the potential barrier between two phases. Here, through studying the nucleation and growth mechanisms of hcp domains in compressed iron, we find that the flatted-octahedral-structure (FOS) is the primary structural unit of the embryo nucleus and phase interface of hcp domains, and the interfacial energy is reduced via formation of FOSs. The phase transition process can be described by the following four stages: (i) Some atoms deviate from their equilibrium positions with the aid of thermal fluctuations to form FOSs with two different deformation directions in the local region; (ii) FOSs with different deformation directions aggregate to form a thin stratified structure like twin-crystal configuration; (iii) The thin stratified structure undergoes a relative slip to form the new hcp phase; (iv) The hcp phase domain grows up through the formation of new FOSs along the phase boundary. In addition, through comparing the time evolution curves of initial single phase domain, we find that the growth rate of single phase domain depends on the loading way and its occurrence time.
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14
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Morphology and growth speed of hcp domains during shock-induced phase transition in iron. Sci Rep 2014; 4:3628. [PMID: 24406750 PMCID: PMC3887381 DOI: 10.1038/srep03628] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 12/11/2013] [Indexed: 11/10/2022] Open
Abstract
Emergence and time evolution of micro-structured new-phase domains play a crucial role in determining the macroscopic physical and mechanical behaviors of iron under shock compression. Here, we investigate, through molecular dynamics simulations and theoretical modelings, shock-induced phase transition process of iron from body-centered-cubic (bcc) to hexagonal-close-packed (hcp) structure. We present a central-moment method and a rolling-ball algorithm to calculate and analyze the morphology and growth speed of the hcp phase domains, and then propose a phase transition model to clarify our derived growth law of the phase domains. We also demonstrate that the new-phase evolution process undergoes three distinguished stages with different time scales of the hcp phase fraction in the system.
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15
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Frenkel AI. Applications of extended X-ray absorption fine-structure spectroscopy to studies of bimetallic nanoparticle catalysts. Chem Soc Rev 2012; 41:8163-78. [DOI: 10.1039/c2cs35174a] [Citation(s) in RCA: 223] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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16
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Torchio R, Kvashnin YO, Pascarelli S, Mathon O, Marini C, Genovese L, Bruno P, Garbarino G, Dewaele A, Occelli F, Loubeyre P. X-ray magnetic circular dichroism measurements in Ni up to 200 GPa: resistant ferromagnetism. PHYSICAL REVIEW LETTERS 2011; 107:237202. [PMID: 22182121 DOI: 10.1103/physrevlett.107.237202] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Indexed: 05/31/2023]
Abstract
The structural stability of fcc Ni over a very large pressure range offers a unique opportunity to experimentally investigate how magnetism is modified by simple compression. K-edge x-ray magnetic circular dichroism (XMCD) shows that fcc Ni is ferromagnetic up to 200 GPa, contradicting recent predictions of an abrupt transition to a paramagnetic state at 160 GPa. Density functional theory calculations point out that the pressure evolution of the K-edge XMCD closely follows that of the p projected orbital moment rather than that of the total spin moment. The disappearance of magnetism in Ni is predicted to occur above 400 GPa.
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Affiliation(s)
- R Torchio
- European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, BP220, 38043 Grenoble Cedex, France
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17
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Monza A, Meffre A, Baudelet F, Rueff JP, d'Astuto M, Munsch P, Huotari S, Lachaize S, Chaudret B, Shukla A. Iron under pressure: "Kohn tweezers" and remnant magnetism. PHYSICAL REVIEW LETTERS 2011; 106:247201. [PMID: 21770592 DOI: 10.1103/physrevlett.106.247201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Indexed: 05/31/2023]
Abstract
In this work we investigate the magnetic and structural properties of bulk Fe and Fe nanoparticles under pressure with x-ray absorption and emission spectroscopies providing answers to two fundamental questions: (a) the chicken-or-egg problem for the magnetic and structural transitions and (b) magnetism in the high pressure hcp phase. The two transitions, inextricably linked in the bulk, are clearly decoupled in the nanoparticles, with the magnetic collapse preceding the structural transition. Ultrafast x-ray emission spectroscopy detects remnant magnetism, probably antiferromagnetic fluctuations, up to pressures of about 40 GPa in the hcp phase. This could be of direct relevance to the superconductivity in ϵ-Fe [K. Shimizu et al., Nature (London) 412, 316 (2001)] through the existence of a quantum critical point and associated magnetic fluctuations.
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Affiliation(s)
- A Monza
- Université Pierre et Marie Curie, IMPMC, CNRS UMR7590, Paris, France
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18
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Sha X, Cohen RE. First-principles studies of electrical resistivity of iron under pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:075401. [PMID: 21411882 DOI: 10.1088/0953-8984/23/7/075401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We investigate the temperature and pressure dependences of the electrical resistivity, thermal conductivity and thermal diffusivity for bcc and hcp Fe using the low-order variational approximation and theoretical transport spectral functions calculated from the first-principles linear response linear-muffin-tin-orbital method in the generalized gradient approximation. The calculated values for the electrical resistivity show a strong increase with temperature and decrease with pressure, and are in agreement with high-temperature shock data. We also discuss the behavior of the electrical resistivity for the bcc→hcp phase transition.
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Affiliation(s)
- Xianwei Sha
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015, USA
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19
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Tolédano P, Katzke H, Machon D. Symmetry-induced collapse of ferromagnetism at the α-ε phase transition in iron. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:466002. [PMID: 21403380 DOI: 10.1088/0953-8984/22/46/466002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The magnetostructural bcc-to-hcp phase transition in iron is analysed theoretically in the framework of the Landau theory of phase transitions. In contrast to recent interpretations which emphasize the driving role of magnetism at the transition, the collapse of the ferromagnetic order in ε-Fe is interpreted as resulting from the large spontaneous strains and the magnitude of the displacive order-parameter involved in the Burgers reconstructive transition mechanism. It yields a direct first-order transition from the ferromagnetic α-phase to the non-magnetic ε-phase, without going across an intermediate magnetic structure.
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Affiliation(s)
- Pierre Tolédano
- Physique des Systèmes Complexes, Université de Picardie, Amiens, France.
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20
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Wang BT, Shao JL, Zhang GC, Li WD, Zhang P. Nucleation of hcp and fcc phases in bcc iron under uniform compression: classical molecular dynamics simulations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:435404. [PMID: 21403328 DOI: 10.1088/0953-8984/22/43/435404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
By classical molecular dynamics simulations employing an embedded atom method potential, we have simulated the bcc to hcp/fcc structural transition in single-crystal iron under uniform compression. Results showed that the transition pressure is different from uniaxial compression and shock loading. The transformation occurs on a picosecond timescale and the transition time decreases along with the increase of pressure. The nucleation and growth of the hcp and fcc phases under constant pressure and temperature are analyzed in detail. The nucleation planes, all belonging to the {110}(bcc) family and parallel to the three compression directions [100], [010], and [001], have been observed. About 20% bcc atoms have transformed to fcc phase under pressure just over the critical point, and under higher pressure the fraction of the fcc phase increases steadily to exceed that of the hcp phase. We have investigated the transition mechanism of iron from initial bcc to hcp/fcc and found that the transition mainly consists of compression, rotation, and shuffle.
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Affiliation(s)
- B T Wang
- Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006, People's Republic of China
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21
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Sikora M, Juhin A, Weng TC, Sainctavit P, Detlefs C, de Groot F, Glatzel P. Strong K-edge magnetic circular dichroism observed in photon-in-photon-out spectroscopy. PHYSICAL REVIEW LETTERS 2010; 105:037202. [PMID: 20867798 DOI: 10.1103/physrevlett.105.037202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2010] [Indexed: 05/20/2023]
Abstract
A large enhancement of the x-ray magnetic circular dichroism is observed at the iron K absorption preedge of magnetite. This is achieved by performing resonant inelastic x-ray scattering (RIXS) experiments with a 2p hole in the final state of the second-order optical process. We measured and calculated the full 1s2p RIXS planes for opposite helicities of the incoming circularly polarized x rays. The crystal field multiplet calculations show that the enhancement arises from 2p-3d Coulomb repulsions and 2p and 3d spin-orbit coupling. The observed magnitude of the RIXS magnetic circular dichroism effect is ∼16%. This opens up new opportunities for a broad range of research fields allowing for truly bulk-sensitive, element-, and site-selective measurements of 3d transition metal magnetic moments and their ordering using hard x-ray photons.
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Affiliation(s)
- Marcin Sikora
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Kraków, Poland.
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22
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Khalid S, Caliebe W, Siddons P, So I, Clay B, Lenhard T, Hanson J, Wang Q, Frenkel AI, Marinkovic N, Hould N, Ginder-Vogel M, Landrot GL, Sparks DL, Ganjoo A. Quick extended x-ray absorption fine structure instrument with millisecond time scale, optimized for in situ applications. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:015105. [PMID: 20113127 DOI: 10.1063/1.3276679] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In order to learn about in situ structural changes in materials at subseconds time scale, we have further refined the techniques of quick extended x-ray absorption fine structure (QEXAFS) and quick x-ray absorption near edge structure (XANES) spectroscopies at beamline X18B at the National Synchrotron Light Source. The channel cut Si (111) monochromator oscillation is driven through a tangential arm at 5 Hz, using a cam, dc motor, pulley, and belt system. The rubber belt between the motor and the cam damps the mechanical noise. EXAFS scan taken in 100 ms is comparable to standard data. The angle and the angular range of the monochromator can be changed to collect a full EXAFS or XANES spectrum in the energy range 4.7-40.0 KeV. The data are recorded in ascending and descending order of energy, on the fly, without any loss of beam time. The QEXAFS mechanical system is outside the vacuum system, and therefore changing the mode of operation from conventional to QEXAFS takes only a few minutes. This instrument allows the acquisition of time resolved data in a variety of systems relevant to electrochemical, photochemical, catalytic, materials, and environmental sciences.
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Affiliation(s)
- S Khalid
- National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, Upton, New York 11973, USA
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23
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Pascarelli S, Mathon O. Advances in high brilliance energy dispersive X-ray absorption spectroscopy. Phys Chem Chem Phys 2010; 12:5535-46. [DOI: 10.1039/b926509k] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Subías G, Cuartero V, García J, Blasco J, Mathon O, Pascarelli S. Pressure-induced magnetic transition in Fe3O4and CoFe2O4spinels. ACTA ACUST UNITED AC 2009. [DOI: 10.1088/1742-6596/190/1/012089] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Baudelet F, Mathon O, Itié JP, Polian A, Kappler JP, Pascarelli S. Magnetic and crystallographic characterization of Pt(3)Mn(x)Cr(1-x) by XMCD and x-ray diffraction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:346003. [PMID: 21715793 DOI: 10.1088/0953-8984/21/34/346003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have performed XMCD and diffraction measurements on the Pt(3)Mn(x)Cr(1-x) alloy, which show that the magnetization of Pt is independently influenced by the Mn or Cr 3d orbital. We find that the magnetic moment on Pt, and its decomposition into spin and orbital components, is uniquely determined by the relative number of Mn and Cr neighbors. We then investigate the effect of pressure on the magnetization of Pt in the Pt(3)Mn(0.5)Cr(0.5) alloy. Our high pressure data enable us to conclude that at 14 GPa the spin and orbital polarization of the Pt 5d band are augmented by about 70%, with no interaction between them.
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Affiliation(s)
- F Baudelet
- IMPMC, CNRS UMR 7590, Université Pierre et Marie Curie Paris6, 140 rue de Lourmel, 75015 Paris, France. Synchrotron-SOLEIL, L'Orme des Merisiers, 91192 Gif-sur-Yvette, France
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26
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Boehler R, Musshoff HG, Ditz R, Aquilanti G, Trapananti A. Portable laser-heating stand for synchrotron applications. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2009; 80:045103. [PMID: 19405687 DOI: 10.1063/1.3115183] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A compact, double-sided laser-heating system for diamond-cell synchrotron applications is described. The optical table, containing laser, spectrometer, and all optics for visual observation and measuring temperatures and pressures has an area of less than 1/2 m(2) and weighs less than 20 kg. All components can be remotely controlled at micron levels with simple dc motors and pneumatic drives. The design allows quick alignment of the laser-heated hot spot with the x-ray beam and the spectrometer. The prealigned system can be set up at most synchrotron beamlines within about 1 h. We carried out measurements on a variety of materials above one megabar and up to over 4000 K at both the x-ray diffraction beamline ID 27 and the x-ray absorption beamline ID 24 at the European Synchrotron Facility. A new measurement of the melting temperature of iron by x-ray absorption spectroscopy is presented.
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Affiliation(s)
- R Boehler
- Max-Planck-Institut fur Chemie, Postfach 3060, D-55020 Mainz, Germany
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27
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van der Linden PJEM, Mathon O, Strohm C, Sikora M. Miniature pulsed magnet system for synchrotron x-ray measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:075104. [PMID: 18681731 DOI: 10.1063/1.2949873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We have developed a versatile experimental apparatus for synchrotron x-ray measurements in pulsed high magnetic fields. The apparatus consists of a double cryostat incorporating a liquid nitrogen bath to cool the miniature pulsed coil and an independent helium flow cryostat allowing sample temperatures from 4 up to 250 K. The high duty cycle miniature pulsed coils can generate up to 38 T. During experiments at 30 T a repetition rate of 6 pulsesmin was routinely reached. Using a 4 kJ power supply, the pulse duration was between 500 mus and 1 ms. The setup was used for nuclear forward scattering measurements on 57Fe up to 25 T on the ESRF beamline ID18. In another experiment, x-ray magnetic circular dichroism was measured up to 30 T on the ESRF energy dispersive beamline ID24.
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Affiliation(s)
- Peter J E M van der Linden
- European Synchrotron Radiation Facility, Polygone Scientifique Louis Neel, 6 rue Jules Horowitz, F-38043 Grenoble, France
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28
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Johnson DF, Carter EA. Nonadiabaticity in the iron bcc to hcp phase transformation. J Chem Phys 2008; 128:104703. [DOI: 10.1063/1.2883592] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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29
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Pascarelli S, Ruffoni MP, Trapananti A, Mathon O, Aquilanti G, Ostanin S, Staunton JB, Pettifer RF. Effect of pressure on magnetoelastic coupling in 3d metal alloys studied with x-ray absorption spectroscopy. PHYSICAL REVIEW LETTERS 2007; 99:237204. [PMID: 18233406 DOI: 10.1103/physrevlett.99.237204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Indexed: 05/25/2023]
Abstract
Using x-ray absorption spectroscopy, we have studied the effect of pressure on femtometer-scale bond strain due to anisotropic magnetostriction in a thin FeCo film. At 7 GPa local magnetostrictive strain is found to be larger than at ambient, in agreement with spin-polarized ab initio electronic structure calculations, but contrary to the expected effect of compression on bond stiffness. The availability of high pressure data on local magnetostrictive strain opens new capabilities for validating theoretical predictions and can lead to the development of materials with the desired properties.
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Affiliation(s)
- S Pascarelli
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France
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Mattila A, Rueff JP, Badro J, Vankó G, Shukla A. Metal-ligand interplay in strongly correlated oxides: a parametrized phase diagram for pressure-induced spin transitions. PHYSICAL REVIEW LETTERS 2007; 98:196404. [PMID: 17677640 DOI: 10.1103/physrevlett.98.196404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Indexed: 05/16/2023]
Abstract
We investigate the magnetic properties of archetypal transition-metal oxides MnO, FeO, CoO, and NiO under very high pressure by x-ray emission spectroscopy at the Kbeta line. We observe a strong modification of the magnetism in the megabar range in all the samples except NiO. The results are analyzed within a multiplet approach including charge-transfer effects. The spectral changes are well accounted for by changes of the ligand field acting on the d electrons and allows us to extract the d-hybridization strength, O-2p bandwidth and ionic crystal field across the magnetic transition. This approach allows first-hand insight into the mechanism of the pressure-induced spin transition.
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Affiliation(s)
- Aleksi Mattila
- Division of X-Ray Physics, Department of Physical Sciences, POB 64, 00014 University of Helsinki, Finland
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