1
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Orr KP, Diao J, Dey K, Hameed M, Dubajić M, Gilbert HL, Selby TA, Zelewski SJ, Han Y, Fitzsimmons MR, Roose B, Li P, Fan J, Jiang H, Briscoe J, Robinson IK, Stranks SD. Strain Heterogeneity and Extended Defects in Halide Perovskite Devices. ACS ENERGY LETTERS 2024; 9:3001-3011. [PMID: 38911532 PMCID: PMC11190982 DOI: 10.1021/acsenergylett.4c00921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 05/13/2024] [Accepted: 05/20/2024] [Indexed: 06/25/2024]
Abstract
Strain is an important property in halide perovskite semiconductors used for optoelectronic applications because of its ability to influence device efficiency and stability. However, descriptions of strain in these materials are generally limited to bulk averages of bare films, which miss important property-determining heterogeneities that occur on the nanoscale and at interfaces in multilayer device stacks. Here, we present three-dimensional nanoscale strain mapping using Bragg coherent diffraction imaging of individual grains in Cs0.1FA0.9Pb(I0.95Br0.05)3 and Cs0.15FA0.85SnI3 (FA = formamidinium) halide perovskite absorbers buried in full solar cell devices. We discover large local strains and striking intragrain and grain-to-grain strain heterogeneity, identifying distinct islands of tensile and compressive strain inside grains. Additionally, we directly image dislocations with surprising regularity in Cs0.15FA0.85SnI3 grains and find evidence for dislocation-induced antiphase boundary formation. Our results shine a rare light on the nanoscale strains in these materials in their technologically relevant device setting.
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Affiliation(s)
- Kieran
W. P. Orr
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
| | - Jiecheng Diao
- Center
for Transformative Science, ShanghaiTech
University, Shanghai 201210, China
| | - Krishanu Dey
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
| | - Madsar Hameed
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, London E1 4NS, U.K.
| | - Miloš Dubajić
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
| | - Hayley L. Gilbert
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
- Diamond
Light Source, Harwell Science and Innovation Campus, Fermi Avenue, Didcot OX11 0DE, U.K.
| | - Thomas A. Selby
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
| | - Szymon J. Zelewski
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
| | - Yutong Han
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
| | - Melissa R. Fitzsimmons
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
| | - Bart Roose
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
| | - Peng Li
- Diamond
Light Source, Harwell Science and Innovation Campus, Fermi Avenue, Didcot OX11 0DE, U.K.
| | - Jiadong Fan
- Center
for Transformative Science, ShanghaiTech
University, Shanghai 201210, China
| | - Huaidong Jiang
- Center
for Transformative Science, ShanghaiTech
University, Shanghai 201210, China
| | - Joe Briscoe
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, London E1 4NS, U.K.
| | - Ian K. Robinson
- London
Centre
for Nanotechnology, University College London, London WC1E 6BT, U.K.
- Condensed
Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11793, United States
| | - Samuel D. Stranks
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
- Center
for Transformative Science, ShanghaiTech
University, Shanghai 201210, China
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2
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Kandel S, Maddali S, Huang X, Nashed YSG, Jacobsen C, Allain M, Hruszkewycz SO. Imaging extended single crystal lattice distortion fields with multi-peak Bragg ptychography. OPTICS EXPRESS 2024; 32:19594-19610. [PMID: 38859091 DOI: 10.1364/oe.516729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/27/2024] [Indexed: 06/12/2024]
Abstract
Recent advances in phase-retrieval-based x-ray imaging methods have demonstrated the ability to reconstruct 3D distortion vector fields within a nanocrystal by using coherent diffraction information from multiple crystal Bragg reflections. However, these works do not provide a solution to the challenges encountered in imaging lattice distortions in crystals with significant defect content that result in phase wrapping. Moreover, these methods only apply to isolated crystals smaller than the x-ray illumination, and therefore cannot be used for imaging of distortions in extended crystals. We introduce multi-peak Bragg ptychography which addresses both challenges via an optimization framework that combines stochastic gradient descent and phase unwrapping methods for robust image reconstruction of lattice distortions and defects in extended crystals. Our work uses modern automatic differentiation toolsets so that the method is easy to extend to other settings and easy to implement in high-performance computers. This work is particularly timely given the broad interest in using the increased coherent flux in fourth-generation synchrotrons for innovative material research.
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3
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Mokhtar AH, Serban D, Porter DG, Lichtenberg F, Collins SP, Bombardi A, Spaldin NA, Newton MC. Three-dimensional domain identification in a single hexagonal manganite nanocrystal. Nat Commun 2024; 15:3587. [PMID: 38678047 PMCID: PMC11055849 DOI: 10.1038/s41467-024-48002-z] [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: 05/09/2023] [Accepted: 04/17/2024] [Indexed: 04/29/2024] Open
Abstract
The three-dimensional domain structure of ferroelectric materials significantly influences their properties. The ferroelectric domain structure of improper multiferroics, such as YMnO3, is driven by a non-ferroelectric order parameter, leading to unique hexagonal vortex patterns and topologically protected domain walls. Characterizing the three-dimensional structure of these domains and domain walls has been elusive, however, due to a lack of suitable imaging techniques. Here, we present a multi-peak Bragg coherent x-ray diffraction imaging determination of the domain structure in single YMnO3 nanocrystals. We resolve two ferroelectric domains separated by a domain wall and confirm that the primary atomic displacements occur along the crystallographic c-axis. Correlation with atomistic simulations confirms the Mexican hat symmetry model of domain formation, identifying two domains with opposite ferroelectric polarization and adjacent trimerization, manifesting in a clockwise arrangement around the hat's brim.
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Affiliation(s)
- Ahmed H Mokhtar
- School of Physics and Astronomy, University of Southampton. University Road, Southampton, SO17 1BJ, UK.
| | - David Serban
- School of Physics and Astronomy, University of Southampton. University Road, Southampton, SO17 1BJ, UK
| | - Daniel G Porter
- Beamline I16, Diamond Light Source. Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Frank Lichtenberg
- Department of Materials, ETH Zurich. Ramistrasse 101, 8092, Zurich, Switzerland
| | - Stephen P Collins
- Beamline I16, Diamond Light Source. Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Alessandro Bombardi
- Beamline I16, Diamond Light Source. Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Nicola A Spaldin
- Department of Materials, ETH Zurich. Ramistrasse 101, 8092, Zurich, Switzerland
| | - Marcus C Newton
- School of Physics and Astronomy, University of Southampton. University Road, Southampton, SO17 1BJ, UK.
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4
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Richard MI, Labat S, Dupraz M, Carnis J, Gao L, Texier M, Li N, Wu L, Hofmann JP, Levi M, Leake SJ, Lazarev S, Sprung M, Hensen EJM, Rabkin E, Thomas O. Anomalous Glide Plane in Platinum Nano- and Microcrystals. ACS NANO 2023; 17:6113-6120. [PMID: 36926832 DOI: 10.1021/acsnano.3c01306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
At the nanoscale, the properties of materials depend critically on the presence of crystal defects. However, imaging and characterizing the structure of defects in three dimensions inside a crystal remain a challenge. Here, by using Bragg coherent diffraction imaging, we observe an unexpected anomalous {110} glide plane in two Pt submicrometer crystals grown by very different processes and having very different morphologies. The structure of the defects (type, associated glide plane, and lattice displacement) is imaged in these faceted Pt crystals. Using this noninvasive technique, both plasticity and unusual defect behavior can be probed at the nanoscale.
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Affiliation(s)
- Marie-Ingrid Richard
- Univ. Grenoble Alpes, CEA Grenoble, IRIG/MEM/NRX, Grenoble 38054, France
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, Grenoble 38000, France
| | - Stéphane Labat
- Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 13397 Marseille, France
| | - Maxime Dupraz
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, Grenoble 38000, France
- Univ. Grenoble Alpes, CEA Grenoble, NRX, 17 Avenue des Martyrs 38000 Grenoble, France
| | - Jérôme Carnis
- Univ. Grenoble Alpes, CEA Grenoble, IRIG/MEM/NRX, Grenoble 38054, France
| | - Lu Gao
- Laboratory for Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Michaël Texier
- Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 13397 Marseille, France
| | - Ni Li
- Univ. Grenoble Alpes, CEA Grenoble, NRX, 17 Avenue des Martyrs 38000 Grenoble, France
| | - Longfei Wu
- Laboratory for Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Jan P Hofmann
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287 Darmstadt, Germany
| | - Mor Levi
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, 3200003, Haifa, Israel
| | - Steven J Leake
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, Grenoble 38000, France
| | - Sergey Lazarev
- Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg, Germany
| | - Michael Sprung
- Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg, Germany
| | - Emiel J M Hensen
- Laboratory for Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Eugen Rabkin
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, 3200003, Haifa, Israel
| | - Olivier Thomas
- Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 13397 Marseille, France
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5
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Botifoll M, Pinto-Huguet I, Arbiol J. Machine learning in electron microscopy for advanced nanocharacterization: current developments, available tools and future outlook. NANOSCALE HORIZONS 2022; 7:1427-1477. [PMID: 36239693 DOI: 10.1039/d2nh00377e] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In the last few years, electron microscopy has experienced a new methodological paradigm aimed to fix the bottlenecks and overcome the challenges of its analytical workflow. Machine learning and artificial intelligence are answering this call providing powerful resources towards automation, exploration, and development. In this review, we evaluate the state-of-the-art of machine learning applied to electron microscopy (and obliquely, to materials and nano-sciences). We start from the traditional imaging techniques to reach the newest higher-dimensionality ones, also covering the recent advances in spectroscopy and tomography. Additionally, the present review provides a practical guide for microscopists, and in general for material scientists, but not necessarily advanced machine learning practitioners, to straightforwardly apply the offered set of tools to their own research. To conclude, we explore the state-of-the-art of other disciplines with a broader experience in applying artificial intelligence methods to their research (e.g., high-energy physics, astronomy, Earth sciences, and even robotics, videogames, or marketing and finances), in order to narrow down the incoming future of electron microscopy, its challenges and outlook.
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Affiliation(s)
- Marc Botifoll
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain.
| | - Ivan Pinto-Huguet
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain.
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain.
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Catalonia, Spain
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6
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Simonne D, Carnis J, Atlan C, Chatelier C, Favre-Nicolin V, Dupraz M, Leake SJ, Zatterin E, Resta A, Coati A, Richard MI. Gwaihir: Jupyter Notebook graphical user interface for Bragg coherent diffraction imaging. J Appl Crystallogr 2022; 55:1045-1054. [PMID: 35974722 PMCID: PMC9348885 DOI: 10.1107/s1600576722005854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 06/01/2022] [Indexed: 11/10/2022] Open
Abstract
In a world where data are steadily made more available, Gwaihir is a tool that overcomes multiple issues by bridging remote access, cluster computing and a user-friendly interface, consequentially improving the link between synchrotrons and their users for Bragg coherent diffraction imaging. Bragg coherent X-ray diffraction is a nondestructive method for probing material structure in three dimensions at the nanoscale, with unprecedented resolution in displacement and strain fields. This work presents Gwaihir, a user-friendly and open-source tool to process and analyze Bragg coherent X-ray diffraction data. It integrates the functionalities of the existing packages bcdi and PyNX in the same toolbox, creating a natural workflow and promoting data reproducibility. Its graphical interface, based on Jupyter Notebook widgets, combines an interactive approach for data analysis with a powerful environment designed to link large-scale facilities and scientists.
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7
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Yang D, Phillips NW, Song K, Barker C, Harder RJ, Cha W, Liu W, Hofmann F. In situ Bragg coherent X-ray diffraction imaging of corrosion in a Co-Fe alloy microcrystal. CrystEngComm 2022; 24:1334-1343. [PMID: 35634094 PMCID: PMC9074767 DOI: 10.1039/d1ce01586a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 01/18/2022] [Indexed: 11/21/2022]
Abstract
Corrosion is a major concern for many industries, as corrosive environments can induce structural and morphological changes that lead to material dissolution and accelerate material failure. The progression of corrosion depends on nanoscale morphology, stress, and defects present. Experimentally monitoring this complex interplay is challenging. Here we implement in situ Bragg coherent X-ray diffraction imaging (BCDI) to probe the dissolution of a Co–Fe alloy microcrystal exposed to hydrochloric acid (HCl). By measuring five Bragg reflections from a single isolated microcrystal at ambient conditions, we compare the full three-dimensional (3D) strain state before corrosion and the strain along the [111] direction throughout the corrosion process. We find that the strained surface layer of the crystal dissolves to leave a progressively less strained surface. Interestingly, the average strain closer to the centre of the crystal increases during the corrosion process. We determine the localised corrosion rate from BCDI data, revealing the preferential dissolution of facets more exposed to the acid stream, highlighting an experimental geometry effect. These results bring new perspectives to understanding the interplay between crystal strain, morphology, and corrosion; a prerequisite for the design of more corrosion-resistant materials. Morphology, 3D lattice strain, and dissolution of a Co–Fe microcrystal was monitored using in situ Bragg coherent X-ray diffraction imaging.![]()
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Affiliation(s)
- David Yang
- Department of Engineering Science, University of Oxford Oxford OX1 3PJ UK
| | | | - Kay Song
- Department of Engineering Science, University of Oxford Oxford OX1 3PJ UK
| | - Clara Barker
- Department of Materials, University of Oxford Oxford OX1 3PH UK
| | - Ross J Harder
- Advanced Photon Source, Argonne National Laboratory Argonne IL 60439 USA
| | - Wonsuk Cha
- Advanced Photon Source, Argonne National Laboratory Argonne IL 60439 USA
| | - Wenjun Liu
- Advanced Photon Source, Argonne National Laboratory Argonne IL 60439 USA
| | - Felix Hofmann
- Department of Engineering Science, University of Oxford Oxford OX1 3PJ UK
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8
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Godard P. On the use of the scattering amplitude in coherent X-ray Bragg diffraction imaging. J Appl Crystallogr 2021. [DOI: 10.1107/s1600576721003113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Lens-less imaging of crystals with coherent X-ray diffraction offers some unique possibilities for strain-field characterization. It relies on numerically retrieving the phase of the scattering amplitude from a crystal illuminated with coherent X-rays. In practice, the algorithms encode this amplitude as a discrete Fourier transform of an effective or Bragg electron density. This short article suggests a detailed route from the classical expression of the (continuous) scattering amplitude to this discrete function. The case of a heterogeneous incident field is specifically detailed. Six assumptions are listed and quantitatively discussed when no such analysis was found in the literature. Details are provided for two of them: the fact that the structure factor varies in the vicinity of the probed reciprocal lattice vector, and the polarization factor, which is heterogeneous along the measured diffraction patterns. With progress in X-ray sources, data acquisition and analysis, it is believed that some approximations will prove inappropriate in the near future.
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9
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Yang D, Phillips NW, Song K, Harder RJ, Cha W, Hofmann F. Annealing of focused ion beam damage in gold microcrystals: an in situ Bragg coherent X-ray diffraction imaging study. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:550-565. [PMID: 33650568 PMCID: PMC7941296 DOI: 10.1107/s1600577520016264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/15/2020] [Indexed: 05/22/2023]
Abstract
Focused ion beam (FIB) techniques are commonly used to machine, analyse and image materials at the micro- and nanoscale. However, FIB modifies the integrity of the sample by creating defects that cause lattice distortions. Methods have been developed to reduce FIB-induced strain; however, these protocols need to be evaluated for their effectiveness. Here, non-destructive Bragg coherent X-ray diffraction imaging is used to study the in situ annealing of FIB-milled gold microcrystals. Two non-collinear reflections are simultaneously measured for two different crystals during a single annealing cycle, demonstrating the ability to reliably track the location of multiple Bragg peaks during thermal annealing. The thermal lattice expansion of each crystal is used to calculate the local temperature. This is compared with thermocouple readings, which are shown to be substantially affected by thermal resistance. To evaluate the annealing process, each reflection is analysed by considering facet area evolution, cross-correlation maps of the displacement field and binarized morphology, and average strain plots. The crystal's strain and morphology evolve with increasing temperature, which is likely to be caused by the diffusion of gallium in gold below ∼280°C and the self-diffusion of gold above ∼280°C. The majority of FIB-induced strains are removed by 380-410°C, depending on which reflection is being considered. These observations highlight the importance of measuring multiple reflections to unambiguously interpret material behaviour.
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Affiliation(s)
- David Yang
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom
| | - Nicholas W. Phillips
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom
| | - Kay Song
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom
| | - Ross J. Harder
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Wonsuk Cha
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Felix Hofmann
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom
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10
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Nanoscale Mapping of Heterogeneous Strain and Defects in Individual Magnetic Nanocrystals. CRYSTALS 2020. [DOI: 10.3390/cryst10080658] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We map the three-dimensional strain heterogeneity within a single core-shell Ni nanoparticle using Bragg coherent diffractive imaging. We report the direct observation of both uniform displacements and strain within the crystalline core Ni region. We identify non-uniform displacements and dislocation morphologies across the core–shell interface, and within the outer shell at the nanoscale. By tracking individual dislocation lines in the outer shell region, and comparing the relative orientation between the Burgers vector and dislocation lines, we identify full and partial dislocations. The full dislocations are consistent with elasticity theory in the vicinity of a dislocation while the partial dislocations deviate from this theory. We utilize atomistic computations and Landau–Lifshitz–Gilbert simulation and density functional theory to confirm the equilibrium shape of the particle and the nature of the (111) displacement field obtained from Bragg coherent diffraction imaging (BCDI) experiments. This displacement field distribution within the core-region of the Ni nanoparticle provides a uniform distribution of magnetization in the core region. We observe that the absence of dislocations within the core-regions correlates with a uniform distribution of magnetization projections. Our findings suggest that the imaging of defects using BCDI could be of significant importance for giant magnetoresistance devices, like hard disk-drive read heads, where the presence of dislocations can affect magnetic domain wall pinning and coercivity.
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11
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Favre-Nicolin V, Leake S, Chushkin Y. Free log-likelihood as an unbiased metric for coherent diffraction imaging. Sci Rep 2020; 10:2664. [PMID: 32060293 PMCID: PMC7021796 DOI: 10.1038/s41598-020-57561-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 12/16/2019] [Indexed: 11/18/2022] Open
Abstract
Coherent Diffraction Imaging (CDI), a technique where an object is reconstructed from a single (2D or 3D) diffraction pattern, recovers the lost diffraction phases without a priori knowledge of the extent (support) of the object. The uncertainty of the object support can lead to over-fitting and prevents an unambiguous metric evaluation of solutions. We propose to use a ‘free’ log-likelihood indicator, where a small percentage of points are masked from the reconstruction algorithms, as an unbiased metric to evaluate the validity of computed solutions, independent of the sample studied. We also show how a set of solutions can be analysed through an eigen-decomposition to yield a better estimate of the real object. Example analysis on experimental data is presented both for a test pattern dataset, and the diffraction pattern from a live cyanobacteria cell. The method allows the validation of reconstructions on a wide range of materials (hard condensed or biological), and should be particularly relevant for 4th generation synchrotrons and X-ray free electron lasers, where large, high-throughput datasets require a method for unsupervised data evaluation.
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Affiliation(s)
- Vincent Favre-Nicolin
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France. .,Univ. Grenoble Alpes, Grenoble, France.
| | - Steven Leake
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Yuriy Chushkin
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France
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12
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Impact and mitigation of angular uncertainties in Bragg coherent x-ray diffraction imaging. Sci Rep 2019; 9:6386. [PMID: 31011168 PMCID: PMC6477045 DOI: 10.1038/s41598-019-42797-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 03/27/2019] [Indexed: 11/08/2022] Open
Abstract
Bragg coherent diffraction imaging (BCDI) is a powerful technique to explore the local strain state and morphology of microscale crystals. The method can potentially reach nanometer-scale spatial resolution thanks to the advances in synchrotron design that dramatically increase coherent flux. However, there are experimental bottlenecks that may limit the image reconstruction quality from future high signal-to-noise ratio measurements. In this work we show that angular uncertainty of the sample orientation with respect to a fixed incoming beam is one example of such a factor, and we present a method to mitigate the resulting artifacts. On the basis of an alternative formulation of the forward problem, we design a phase retrieval algorithm which enables the simultaneous reconstruction of the object and determination of the exact angular position corresponding to each diffraction pattern in the data set. We have tested the algorithm performance on simulated data for different degrees of angular uncertainty and signal-to-noise ratio.
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13
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Cherukara MJ, Nashed YSG, Harder RJ. Real-time coherent diffraction inversion using deep generative networks. Sci Rep 2018; 8:16520. [PMID: 30410034 PMCID: PMC6224523 DOI: 10.1038/s41598-018-34525-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 10/19/2018] [Indexed: 11/11/2022] Open
Abstract
Phase retrieval, or the process of recovering phase information in reciprocal space to reconstruct images from measured intensity alone, is the underlying basis to a variety of imaging applications including coherent diffraction imaging (CDI). Typical phase retrieval algorithms are iterative in nature, and hence, are time-consuming and computationally expensive, making real-time imaging a challenge. Furthermore, iterative phase retrieval algorithms struggle to converge to the correct solution especially in the presence of strong phase structures. In this work, we demonstrate the training and testing of CDI NN, a pair of deep deconvolutional networks trained to predict structure and phase in real space of a 2D object from its corresponding far-field diffraction intensities alone. Once trained, CDI NN can invert a diffraction pattern to an image within a few milliseconds of compute time on a standard desktop machine, opening the door to real-time imaging.
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Affiliation(s)
- Mathew J Cherukara
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA.
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, 60439, USA.
| | - Youssef S G Nashed
- Mathematics and Computer Science, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Ross J Harder
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
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14
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Mordehai D, David O, Kositski R. Nucleation-Controlled Plasticity of Metallic Nanowires and Nanoparticles. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1706710. [PMID: 29962014 DOI: 10.1002/adma.201706710] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 03/16/2018] [Indexed: 06/08/2023]
Abstract
Nanowires and nanoparticles are envisioned as important elements of future technology and devices, owing to their unique mechanical properties. Metallic nanowires and nanoparticles demonstrate outstanding size-dependent strength since their deformation is dislocation nucleation-controlled. In this context, the recent experimental and computational studies of nucleation-controlled plasticity are reviewed. The underlying microstructural mechanisms that govern the strength of nanowires and the origin of their stochastic nature are also discussed. Nanoparticles, in which the stress state under compression is nonuniform, exhibit a shape-dependent strength. Perspectives on improved methods to study nucleation-controlled plasticity are discussed, as well the insights gained for microstructural-based design of mechanical properties at the nanoscale.
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Affiliation(s)
- Dan Mordehai
- Department of Mechanical Engineering, Technion-Israel Institute of Technology, 32000, Haifa, Israel
| | - Omer David
- Department of Mechanical Engineering, Technion-Israel Institute of Technology, 32000, Haifa, Israel
| | - Roman Kositski
- Department of Mechanical Engineering, Technion-Israel Institute of Technology, 32000, Haifa, Israel
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