1
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Lewis GR, Wolf D, Lubk A, Ringe E, Midgley PA. WRAP: A wavelet-regularised reconstruction algorithm for magnetic vector electron tomography. Ultramicroscopy 2023; 253:113804. [PMID: 37481909 DOI: 10.1016/j.ultramic.2023.113804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/09/2023] [Accepted: 06/30/2023] [Indexed: 07/25/2023]
Abstract
Magnetic vector electron tomography (VET) is a promising technique that enables better understanding of micro- and nano-magnetic phenomena through the reconstruction of 3D magnetic fields at high spatial resolution. Here we introduce WRAP (Wavelet Regularised A Program), a reconstruction algorithm for magnetic VET that directly reconstructs the magnetic vector potential A using a compressed sensing framework which regularises for sparsity in the wavelet domain. We demonstrate that using WRAP leads to a significant increase in the fidelity of the 3D reconstruction and is especially robust when dealing with very limited data; using datasets simulated with realistic noise, we compare WRAP to a conventional reconstruction algorithm and find an improvement of ca. 60% when averaged over several performance metrics. Moreover, we further validate WRAP's performance on experimental electron holography data, revealing the detailed magnetism of vortex states in a CuCo nanowire. We believe WRAP represents a major step forward in the development of magnetic VET as a tool for probing magnetism at the nanoscale.
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Affiliation(s)
- George R Lewis
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK; Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK
| | - Daniel Wolf
- Institute for Solid State Research, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany
| | - Axel Lubk
- Institute for Solid State Research, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany; Institute of Solid State and Materials Physics, TU Dresden, 01062 Dresden, Germany
| | - Emilie Ringe
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK; Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK
| | - Paul A Midgley
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK
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2
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Zhang Z, Bercovici D. Generation of a measurable magnetic field in a metal asteroid with a rubble-pile core. Proc Natl Acad Sci U S A 2023; 120:e2221696120. [PMID: 37523545 PMCID: PMC10410757 DOI: 10.1073/pnas.2221696120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 06/21/2023] [Indexed: 08/02/2023] Open
Abstract
Paleomagnetic records of iron meteorites of the IVA group suggest that their parent body (an inward-solidified metal asteroid) possessed an internal magnetic field. The origin of this magnetism is enigmatic because inward solidification typically leads to light element release from the top of the liquid, which depresses convection and dynamo activity. Here, we propose a possible scenario to help resolve this paradox. The formation of a metal asteroid must involve a disruptive, mantle-stripping collision and the reaccretion of metal fragments. We hypothesize that a small portion of metal fragments may have substantially cooled before being reaccreted. These fragments could have formed a cold, rubble-pile inner core, which extracted heat from the liquid layer, leading to solidification and light element expulsion at the inner core boundary to power a dynamo. In the portions of the inward-growing crust that cooled below the remanence acquisition temperature, the magnetic field could be recorded.
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Affiliation(s)
- Zhongtian Zhang
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT06511
| | - David Bercovici
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT06511
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3
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Lewis GR, Ringe E, Midgley PA. Cones and spirals: Multi-axis acquisition for scalar and vector electron tomography. Ultramicroscopy 2023; 252:113775. [PMID: 37295062 DOI: 10.1016/j.ultramic.2023.113775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023]
Abstract
Electron tomography (ET) has become an important tool for understanding the 3D nature of nanomaterials, with recent developments enabling not only scalar reconstructions of electron density, but also vector reconstructions of magnetic fields. However, whilst new signals have been incorporated into the ET toolkit, the acquisition schemes have largely kept to conventional single-axis tilt series for scalar ET, and dual-axis schemes for magnetic vector ET. In this work, we explore the potential of using multi-axis tilt schemes including conical and spiral tilt schemes to improve reconstruction fidelity in scalar and magnetic vector ET. Through a combination of systematic simulations and a proof-of-concept experiment, we show that spiral and conical tilt schemes have the potential to produce substantially improved reconstructions, laying the foundations of a new approach to electron tomography acquisition and reconstruction.
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Affiliation(s)
- George R Lewis
- Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS, UK; Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
| | - Emilie Ringe
- Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS, UK; Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
| | - Paul A Midgley
- Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS, UK
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4
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Weiss BP, Merayo JMG, Ream JB, Oran R, Brauer P, Cochrane CJ, Cloutier K, Elkins-Tanton LT, Jørgensen JL, Maurel C, Park RS, Polanskey CA, de Soria Santacruz-Pich M, Raymond CA, Russell CT, Wenkert D, Wieczorek MA, Zuber MT. The Psyche Magnetometry Investigation. SPACE SCIENCE REVIEWS 2023; 219:22. [PMID: 37007705 PMCID: PMC10049963 DOI: 10.1007/s11214-023-00965-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/01/2023] [Indexed: 06/01/2023]
Abstract
The objective of the Psyche Magnetometry Investigation is to test the hypothesis that asteroid (16) Psyche formed from the core of a differentiated planetesimal. To address this, the Psyche Magnetometer will measure the magnetic field around the asteroid to search for evidence of remanent magnetization. Paleomagnetic measurements of meteorites and dynamo theory indicate that a diversity of planetesimals once generated dynamo magnetic fields in their metallic cores. Likewise, the detection of a strong magnetic moment ( > 2 × 10 14 Am 2 ) at Psyche would likely indicate that the body once generated a core dynamo, implying that it formed by igneous differentiation. The Psyche Magnetometer consists of two three-axis fluxgate Sensor Units (SUs) mounted 0.7 m apart along a 2.15-m long boom and connected to two Electronics Units (EUs) located within the spacecraft bus. The Magnetometer samples at up to 50 Hz, has a range of ± 80 , 000 nT , and an instrument noise of 39 pT axis - 1 3 σ integrated over 0.1 to 1 Hz. The two pairs of SUs and EUs provide redundancy and enable gradiometry measurements to suppress noise from flight system magnetic fields. The Magnetometer will be powered on soon after launch and acquire data for the full duration of the mission. The ground data system processes the Magnetometer measurements to obtain an estimate of Psyche's dipole moment.
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Affiliation(s)
- Benjamin P Weiss
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA USA
| | - José M G Merayo
- DTU Space, Technical University of Denmark (DTU), Copenhagen, Denmark
| | - Jodie B Ream
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA USA
| | - Rona Oran
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA USA
| | - Peter Brauer
- DTU Space, Technical University of Denmark (DTU), Copenhagen, Denmark
| | - Corey J Cochrane
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA USA
| | - Kyle Cloutier
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA USA
| | | | - John L Jørgensen
- DTU Space, Technical University of Denmark (DTU), Copenhagen, Denmark
| | - Clara Maurel
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA USA
| | - Ryan S Park
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA USA
| | - Carol A Polanskey
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA USA
| | | | - Carol A Raymond
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA USA
| | - Christopher T Russell
- Department of Earth and Space Sciences, University of California, Los Angeles, Los Angeles, CA USA
| | - Daniel Wenkert
- Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA USA
| | - Mark A Wieczorek
- Observatoire de la Côte d'Azur, Centre National de la Recherche Scientifique (CNRS), Laboratoire Lagrange, Université Côte d'Azur, Nice, France
| | - Maria T Zuber
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA USA
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5
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Sheikh HA, Tung PY, Ringe E, Harrison RJ. Magnetic and microscopic investigation of airborne iron oxide nanoparticles in the London Underground. Sci Rep 2022; 12:20298. [PMID: 36522360 PMCID: PMC9755232 DOI: 10.1038/s41598-022-24679-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/18/2022] [Indexed: 12/23/2022] Open
Abstract
Particulate matter (PM) concentration levels in the London Underground (LU) are higher than London background levels and beyond World Health Organization (WHO) defined limits. Wheel, track, and brake abrasion are the primary sources of particulate matter, producing predominantly Fe-rich particles that make the LU microenvironment particularly well suited to study using environmental magnetism. Here we combine magnetic properties, high-resolution electron microscopy, and electron tomography to characterize the structure, chemistry, and morphometric properties of LU particles in three dimensions with nanoscale resolution. Our findings show that LU PM is dominated by 5-500 nm particles of maghemite, occurring as 0.1-2 μm aggregated clusters, skewing the size-fractioned concentration of PM artificially to larger sizes when measured with traditional monitors. Magnetic properties are largely independent of the PM filter size (PM10, PM4, and PM2.5), and demonstrate the presence of superparamagnetic (< 30 nm), single-domain (30-70 nm), and vortex/pseudo-single domain (70-700 nm) signals only (i.e., no multi-domain particles > 1 µm). The oxidized nature of the particles suggests that PM exposure in the LU is dominated by resuspension of aged dust particles relative to freshly abraded, metallic particles from the wheel/track/brake system, suggesting that periodic removal of accumulated dust from underground tunnels might provide a cost-effective strategy for reducing exposure. The abundance of ultrafine particles identified here could have particularly adverse health impacts as their smaller size makes it possible to pass from lungs to the blood stream. Magnetic methods are shown to provide an accurate assessment of ultrafine PM characteristics, providing a robust route to monitoring, and potentially mitigating this hazard.
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Affiliation(s)
- H. A. Sheikh
- grid.5335.00000000121885934Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ UK
| | - P. Y. Tung
- grid.5335.00000000121885934Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ UK ,grid.5335.00000000121885934Department of Materials Sciences, University of Cambridge, Cambridge, CB3 0FS UK
| | - E. Ringe
- grid.5335.00000000121885934Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ UK ,grid.5335.00000000121885934Department of Materials Sciences, University of Cambridge, Cambridge, CB3 0FS UK
| | - R. J. Harrison
- grid.5335.00000000121885934Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ UK
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6
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Kovács A, Lewis LH, Palanisamy D, Denneulin T, Schwedt A, Scott ER, Gault B, Raabe D, Dunin-Borkowski RE, Charilaou M. Discovery and Implications of Hidden Atomic-Scale Structure in a Metallic Meteorite. NANO LETTERS 2021; 21:8135-8142. [PMID: 34529916 PMCID: PMC8519181 DOI: 10.1021/acs.nanolett.1c02573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Indexed: 06/13/2023]
Abstract
Iron and its alloys have made modern civilization possible, with metallic meteorites providing one of the human's earliest sources of usable iron as well as providing a window into our solar system's billion-year history. Here highest-resolution tools reveal the existence of a previously hidden FeNi nanophase within the extremely slowly cooled metallic meteorite NWA 6259. This new nanophase exists alongside Ni-poor and Ni-rich nanoprecipitates within a matrix of tetrataenite, the uniaxial, chemically ordered form of FeNi. The ferromagnetic nature of the nanoprecipitates combined with the antiferromagnetic character of the FeNi nanophases gives rise to a complex magnetic state that evolves dramatically with temperature. These observations extend and possibly alter our understanding of celestial metallurgy, provide new knowledge concerning the archetypal Fe-Ni phase diagram and supply new information for the development of new types of sustainable, technologically critical high-energy magnets.
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Affiliation(s)
- András Kovács
- Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum
Jülich GmbH, 52425 Jülich, Germany
| | - Laura H. Lewis
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
- Department
of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | | | - Thibaud Denneulin
- Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum
Jülich GmbH, 52425 Jülich, Germany
| | - Alexander Schwedt
- Central
Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen, Germany
| | - Edward R.D. Scott
- Hawaii
Institute of Geophysics and Planetology, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Baptiste Gault
- Max-Planck-Institut
für Eisenforschung, 40237 Düsseldorf, Germany
- Department
of Materials, Royal School of Mines, Imperial
College London, London, SW7 2BP, U.K.
| | - Dierk Raabe
- Max-Planck-Institut
für Eisenforschung, 40237 Düsseldorf, Germany
| | - Rafal E. Dunin-Borkowski
- Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum
Jülich GmbH, 52425 Jülich, Germany
| | - Michalis Charilaou
- Department
of Physics, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
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7
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Jacob M, Gueddari LE, Lin JM, Navarro G, Jannaud A, Mula G, Bayle-Guillemaud P, Ciuciu P, Saghi Z. Gradient-based and wavelet-based compressed sensing approaches for highly undersampled tomographic datasets. Ultramicroscopy 2021; 225:113289. [PMID: 33906008 DOI: 10.1016/j.ultramic.2021.113289] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/29/2021] [Accepted: 04/10/2021] [Indexed: 11/28/2022]
Abstract
Electron tomography is widely employed for the 3D morphological characterization at the nanoscale. In recent years, there has been a growing interest in analytical electron tomography (AET) as it is capable of providing 3D information about the elemental composition, chemical bonding and optical/electronic properties of nanomaterials. AET requires advanced reconstruction algorithms as the datasets often consist of a very limited number of projections. Total variation (TV)-based compressed sensing approaches were shown to provide high-quality reconstructions from undersampled datasets, but staircasing artefacts can appear when the assumption about piecewise constancy does not hold. In this paper, we compare higher-order TV and wavelet-based approaches for AET applications and provide an open-source Python toolbox, Pyetomo, containing 2D and 3D implementations of both methods. A highly sampled STEM-HAADF dataset of an Er-doped porous Si sample and a heavily undersampled STEM-EELS dataset of a Ge-rich GeSbTe (GST) thin film annealed at 450°C are used to evaluate the performance of the different approaches. We show that polynomial annihilation with order 3 (HOTV3) and the Bior4.4 wavelet outperform the classical TV minimization and the related Haar wavelet.
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Affiliation(s)
- Martin Jacob
- Univ. Grenoble Alpes, CEA, LETI, Grenoble F-38000, France.
| | - Loubna El Gueddari
- Univ. Paris Saclay, CEA-NeuroSpin, INRIA, Parietal, Gif-sur-Yvette, F-91191, France.
| | - Jyh-Miin Lin
- Univ. Grenoble Alpes, CEA, LETI, Grenoble F-38000, France.
| | | | - Audrey Jannaud
- Univ. Grenoble Alpes, CEA, LETI, Grenoble F-38000, France.
| | - Guido Mula
- Dipartimento di Fisica, Cittadella Universitaria di Monserrato, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042, Monserrato (Ca), Italy.
| | | | - Philippe Ciuciu
- Univ. Paris Saclay, CEA-NeuroSpin, INRIA, Parietal, Gif-sur-Yvette, F-91191, France.
| | - Zineb Saghi
- Univ. Grenoble Alpes, CEA, LETI, Grenoble F-38000, France.
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8
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Johnstone DN, Firth FCN, Grey CP, Midgley PA, Cliffe MJ, Collins SM. Direct Imaging of Correlated Defect Nanodomains in a Metal-Organic Framework. J Am Chem Soc 2020. [PMID: 32627544 DOI: 10.26434/chemrxiv.12024402.v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Defect engineering can enhance key properties of metal-organic frameworks (MOFs). Tailoring the distribution of defects, for example in correlated nanodomains, requires characterization across length scales. However, a critical nanoscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the subnanometer imaging used to observe individual defects. Here, we demonstrate that the emerging technique of scanning electron diffraction (SED) can bridge this gap uniquely enabling both nanoscale crystallographic analysis and the low-dose formation of multiple diffraction contrast images for defect analysis in MOFs. We directly image defect nanodomains in the MOF UiO-66(Hf) over an area of ca. 1000 nm and with a spatial resolution ca. 5 nm to reveal domain morphology and distribution. Based on these observations, we suggest possible crystal growth processes underpinning synthetic control of defect nanodomains. We also identify likely dislocations and small angle grain boundaries, illustrating that SED could be a key technique in developing the potential for engineering the distribution of defects, or "microstructure", in functional MOF design.
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Affiliation(s)
- Duncan N Johnstone
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, U.K
| | - Francesca C N Firth
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Clare P Grey
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Paul A Midgley
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, U.K
| | - Matthew J Cliffe
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K
| | - Sean M Collins
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, U.K
- School of Chemical and Process Engineering and School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
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9
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Johnstone DN, Firth FCN, Grey CP, Midgley PA, Cliffe MJ, Collins SM. Direct Imaging of Correlated Defect Nanodomains in a Metal-Organic Framework. J Am Chem Soc 2020; 142:13081-13089. [PMID: 32627544 PMCID: PMC7467717 DOI: 10.1021/jacs.0c04468] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Indexed: 11/30/2022]
Abstract
Defect engineering can enhance key properties of metal-organic frameworks (MOFs). Tailoring the distribution of defects, for example in correlated nanodomains, requires characterization across length scales. However, a critical nanoscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the subnanometer imaging used to observe individual defects. Here, we demonstrate that the emerging technique of scanning electron diffraction (SED) can bridge this gap uniquely enabling both nanoscale crystallographic analysis and the low-dose formation of multiple diffraction contrast images for defect analysis in MOFs. We directly image defect nanodomains in the MOF UiO-66(Hf) over an area of ca. 1000 nm and with a spatial resolution ca. 5 nm to reveal domain morphology and distribution. Based on these observations, we suggest possible crystal growth processes underpinning synthetic control of defect nanodomains. We also identify likely dislocations and small angle grain boundaries, illustrating that SED could be a key technique in developing the potential for engineering the distribution of defects, or "microstructure", in functional MOF design.
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Affiliation(s)
- Duncan N. Johnstone
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, U.K.
| | - Francesca C. N. Firth
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
| | - Clare P. Grey
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
| | - Paul A. Midgley
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, U.K.
| | - Matthew J. Cliffe
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Sean M. Collins
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, U.K.
- School
of Chemical and Process Engineering and School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K.
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10
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Maurel C, Bryson JFJ, Lyons RJ, Ball MR, Chopdekar RV, Scholl A, Ciesla FJ, Bottke WF, Weiss BP. Meteorite evidence for partial differentiation and protracted accretion of planetesimals. SCIENCE ADVANCES 2020; 6:eaba1303. [PMID: 32754636 PMCID: PMC7381086 DOI: 10.1126/sciadv.aba1303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 06/09/2020] [Indexed: 06/02/2023]
Abstract
Modern meteorite classification schemes assume that no single planetary body could be source of both unmelted (chondritic) and melted (achondritic) meteorites. This dichotomy is a natural outcome of formation models assuming that planetesimal accretion occurred nearly instantaneously. However, it has recently been proposed that the accretion of many planetesimals lasted over ≳1 million years (Ma). This could have resulted in partially differentiated internal structures, with individual bodies containing iron cores, achondritic silicate mantles, and chondritic crusts. This proposal can be tested by searching for a meteorite group containing evidence for these three layers. We combine synchrotron paleomagnetic analyses with thermal, impact, and collisional evolution models to show that the parent body of the enigmatic IIE iron meteorites was such a partially differentiated planetesimal. This implies that some chondrites and achondrites simultaneously coexisted on the same planetesimal, indicating that accretion was protracted and that apparently undifferentiated asteroids may contain melted interiors.
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Affiliation(s)
- Clara Maurel
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - James F. J. Bryson
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 1TN, UK
| | - Richard J. Lyons
- Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637, USA
| | - Matthew R. Ball
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 1TN, UK
| | - Rajesh V. Chopdekar
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Andreas Scholl
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Fred J. Ciesla
- Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637, USA
| | - William F. Bottke
- Southwest Research Institute and NASA Solar System Exploration Research Virtual Institute–Institute for the Science of Exploration Targets, Boulder, CO 80302, USA
| | - Benjamin P. Weiss
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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11
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McAuliffe TP, Foden A, Bilsland C, Daskalaki Mountanou D, Dye D, Britton TB. Advancing characterisation with statistics from correlative electron diffraction and X-ray spectroscopy, in the scanning electron microscope. Ultramicroscopy 2020; 211:112944. [PMID: 32000031 DOI: 10.1016/j.ultramic.2020.112944] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 01/14/2020] [Accepted: 01/19/2020] [Indexed: 11/19/2022]
Abstract
The routine and unique determination of minor phases in microstructures is critical to materials science. In metallurgy alone, applications include alloy and process development and the understanding of degradation in service. We develop a correlative method, exploring superalloy microstructures, which are examined in the scanning electron microscope (SEM) using simultaneous energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD). This is performed at an appropriate length scale for characterisation of carbide phases' shape, size, location, and distribution. EDS and EBSD data are generated using two different physical processes, but each provide a signature of the material interacting with the incoming electron beam. Recent advances in post-processing, driven by 'big data' approaches, include use of principal component analysis (PCA). Components are subsequently characterised to assign labels to a mapped region. To provide physically meaningful signals, the principal components may be rotated to control the distribution of variance. In this work, we develop this method further through a weighted PCA approach. We use the EDS and EBSD signals concurrently, thereby labelling each region using both EDS (chemistry) and EBSD (crystal structure) information. This provides a new method of amplifying signal-to-noise for very small phases in mapped regions, especially where the EDS or EBSD signal is not unique enough alone for classification.
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Affiliation(s)
- T P McAuliffe
- Department of Materials, Prince Consort Road, Imperial College London, London SW7 2AZ, United Kingdom.
| | - A Foden
- Department of Materials, Prince Consort Road, Imperial College London, London SW7 2AZ, United Kingdom
| | - C Bilsland
- Department of Materials, Prince Consort Road, Imperial College London, London SW7 2AZ, United Kingdom
| | - D Daskalaki Mountanou
- Department of Materials, Prince Consort Road, Imperial College London, London SW7 2AZ, United Kingdom
| | - D Dye
- Department of Materials, Prince Consort Road, Imperial College London, London SW7 2AZ, United Kingdom
| | - T B Britton
- Department of Materials, Prince Consort Road, Imperial College London, London SW7 2AZ, United Kingdom
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12
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BERGH T, JOHNSTONE D, CROUT P, HØGÅS S, MIDGLEY P, HOLMESTAD R, VULLUM P, HELVOORT AVAN. Nanocrystal segmentation in scanning precession electron diffraction data. J Microsc 2019; 279:158-167. [DOI: 10.1111/jmi.12850] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/10/2019] [Accepted: 11/27/2019] [Indexed: 11/28/2022]
Affiliation(s)
- T. BERGH
- Department of PhysicsNorwegian University of Science and Technology (NTNU)Trondheim Norway
| | - D.N. JOHNSTONE
- Department of Materials Science and MetallurgyUniversity of CambridgeCambridge U.K
| | - P. CROUT
- Department of Materials Science and MetallurgyUniversity of CambridgeCambridge U.K
| | - S. HØGÅS
- Department of PhysicsNorwegian University of Science and Technology (NTNU)Trondheim Norway
| | - P.A. MIDGLEY
- Department of Materials Science and MetallurgyUniversity of CambridgeCambridge U.K
| | - R. HOLMESTAD
- Department of PhysicsNorwegian University of Science and Technology (NTNU)Trondheim Norway
| | - P.E. VULLUM
- Department of PhysicsNorwegian University of Science and Technology (NTNU)Trondheim Norway
- Department of Materials and NanotechnologySINTEF IndustryTrondheim Norway
| | - A.T.J. VAN HELVOORT
- Department of PhysicsNorwegian University of Science and Technology (NTNU)Trondheim Norway
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