1
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Folastre N, Cao J, Oney G, Park S, Jamali A, Masquelier C, Croguennec L, Veron M, Rauch EF, Demortière A. Improved ACOM pattern matching in 4D-STEM through adaptive sub-pixel peak detection and image reconstruction. Sci Rep 2024; 14:12385. [PMID: 38811806 PMCID: PMC11137144 DOI: 10.1038/s41598-024-63060-5] [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: 12/09/2023] [Accepted: 05/24/2024] [Indexed: 05/31/2024] Open
Abstract
The technique known as 4D-STEM has recently emerged as a powerful tool for the local characterization of crystalline structures in materials, such as cathode materials for Li-ion batteries or perovskite materials for photovoltaics. However, the use of new detectors optimized for electron diffraction patterns and other advanced techniques requires constant adaptation of methodologies to address the challenges associated with crystalline materials. In this study, we present a novel image-processing method to improve pattern matching in the determination of crystalline orientations and phases. Our approach uses sub-pixel adaptive image processing to register and reconstruct electron diffraction signals in large 4D-STEM datasets. By using adaptive prominence and linear filters, we can improve the quality of the diffraction pattern registration. The resulting data compression rate of 103 is well-suited for the era of big data and provides a significant enhancement in the performance of the entire ACOM data processing method. Our approach is evaluated using dedicated metrics, which demonstrate a high improvement in phase recognition. Several features are extracted from the registered data to map properties such as the spot count, and various virtual dark fields, which are used to enhance the handling of the results maps. Our results demonstrate that this data preparation method not only enhances the quality of the resulting image but also boosts the confidence level in the analysis of the outcomes related to determining crystal orientation and phase. Additionally, it mitigates the impact of user bias that may occur during the application of the method through the manipulation of parameters.
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Affiliation(s)
- Nicolas Folastre
- Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS-UPJV UMR 7314, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
| | - Junhao Cao
- Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS-UPJV UMR 7314, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
| | - Gozde Oney
- Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS-UPJV UMR 7314, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
- Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Bordeaux, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
| | - Sunkyu Park
- Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS-UPJV UMR 7314, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
- Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Bordeaux, France
| | - Arash Jamali
- Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS-UPJV UMR 7314, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
| | - Christian Masquelier
- Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS-UPJV UMR 7314, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
- ALISTORE-European Research Institute, CNRS FR 3104, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
| | - Laurence Croguennec
- Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Bordeaux, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
- ALISTORE-European Research Institute, CNRS FR 3104, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France
| | - Muriel Veron
- Université Grenoble Alpes, CNRS, Grenoble INP, SIMAP, 38000, Grenoble, France
| | - Edgar F Rauch
- Université Grenoble Alpes, CNRS, Grenoble INP, SIMAP, 38000, Grenoble, France
| | - Arnaud Demortière
- Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS-UPJV UMR 7314, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France.
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France.
- ALISTORE-European Research Institute, CNRS FR 3104, Hub de l'Energie, rue Baudelocque, 80039, Amiens Cedex, France.
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2
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Baucom G, Hershkovitz E, Chojecki P, Nishida T, Tabrizian R, Kim H. Nanoscale Phase and Orientation Mapping in Multiphase Polycrystalline Hafnium Zirconium Oxide Thin Films Using 4D-STEM and Automated Diffraction Indexing. SMALL METHODS 2024:e2400395. [PMID: 38754074 DOI: 10.1002/smtd.202400395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/01/2024] [Indexed: 05/18/2024]
Abstract
Ferroelectric hafnium zirconium oxide (HZO) holds promise for nextgeneration memory and transistors due to its superior scalability and seamless integration with complementary metal-oxide-semiconductor processing. A major challenge in developing this emerging ferroelectric material is the metastable nature of the non-centrosymmetric polar phase responsible for ferroelectricity, resulting in a coexistence of both polar and non-polar phases with uneven grain sizes and random orientations. Due to the structural similarity between the multiple phases and the nanoscale dimensions of the thin film devices, accurate measurement of phase-specific information remains challenging. Here, the application of 4D scanning transmission electron microscopy is demonstrated with automated electron diffraction pattern indexing to analyze multiphase polycrystalline HZO thin films, enabling the characterization of crystallographic phase and orientation across large working areas on the order of hundreds of nanometers. This approach offers a powerful characterization framework to produce a quantitative and statistically robust analysis of the intricate structure of HZO films by uncovering phase composition, polarization axis alignment, and unique phase distribution within the HZO film. This study introduces a novel approach for analyzing ferroelectric HZO, facilitating reliable characterization of process-structure-property relationships imperative to accelerating the growth optimization, performance, and successful implementation of ferroelectric HZO in devices.
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Affiliation(s)
- Garrett Baucom
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Eitan Hershkovitz
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Paul Chojecki
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Toshikazu Nishida
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Roozbeh Tabrizian
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Honggyu Kim
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
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3
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Corrêa LM, Ortega E, Ponce A, Cotta MA, Ugarte D. High precision orientation mapping from 4D-STEM precession electron diffraction data through quantitative analysis of diffracted intensities. Ultramicroscopy 2024; 259:113927. [PMID: 38330596 DOI: 10.1016/j.ultramic.2024.113927] [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: 08/02/2023] [Revised: 01/09/2024] [Accepted: 01/21/2024] [Indexed: 02/10/2024]
Abstract
The association of scanning transmission electron microscopy (STEM) and detection of a diffraction pattern at each probe position (so-called 4D-STEM) represents one of the most promising approaches to analyze structural properties of materials with nanometric resolution and low irradiation levels. This is widely used for texture analysis of materials using automated crystal orientation mapping (ACOM). Herein, we perform orientation mapping in InP nanowires exploiting precession electron diffraction (PED) patterns acquired by an axial CMOS camera. Crystal orientation is determined at each probe position by the quantitative analysis of diffracted intensities minimizing a residue comparing experiments and simulations in analogy to x-ray structural refinement. Our simulations are based on the two-beam dynamical diffraction approximation and yield a high angular precision (∼0.03°), much lower than the traditional ACOM based on pattern matching algorithms (∼1°). We anticipate that simultaneous exploration of both spot positions and high precision crystal misorientation will allow the exploration of the whole potentiality provided by PED-based 4D-STEM for the characterization of deformation fields in nanomaterials.
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Affiliation(s)
- Leonardo M Corrêa
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| | - Eduardo Ortega
- Department of Physics and Astronomy, University of Texas, San Antonio, TX 78249, United States
| | - Arturo Ponce
- Department of Physics and Astronomy, University of Texas, San Antonio, TX 78249, United States
| | - Mônica A Cotta
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| | - Daniel Ugarte
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil.
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4
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MacLaren I, Frutos-Myro E, Zeltmann S, Ophus C. A method for crystallographic mapping of an alpha-beta titanium alloy with nanometre resolution using scanning precession electron diffraction and open-source software libraries. J Microsc 2024. [PMID: 38353362 DOI: 10.1111/jmi.13275] [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: 10/16/2023] [Revised: 12/21/2023] [Accepted: 01/30/2024] [Indexed: 02/21/2024]
Abstract
An approach for the crystallographic mapping of two-phase alloys on the nanoscale using a combination of scanned precession electron diffraction and open-source python libraries is introduced in this paper. This method is demonstrated using the example of a two-phase α/β titanium alloy. The data were recorded using a direct electron detector to collect the patterns, and recently developed algorithms to perform automated indexing and analyse the crystallography from the results. Very high-quality mapping is achieved at a 3 nm step size. The results show the expected Burgers orientation relationships between the α laths and β matrix, as well as the expected misorientations between α laths. A minor issue was found that one area was affected by 180° ambiguities in indexing occur due to this area being aligned too close to a zone axis of the α with twofold projection symmetry (not present in 3D) in the zero-order Laue Zone, and this should be avoided in data acquisition in the future. Nevertheless, this study demonstrates a good workflow for the analysis of nanocrystalline two- or multi-phase materials, which will be of widespread use in analysing two-phase titanium and other systems and how they evolve as a function of thermomechanical treatments.
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Affiliation(s)
- Ian MacLaren
- School of Physics and Astronomy, University of Glasgow, Glasgow, UK
| | - Enrique Frutos-Myro
- School of Physics and Astronomy, University of Glasgow, Glasgow, UK
- School of Engineering, University of Glasgow, Glasgow, UK
| | - Steven Zeltmann
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University, Ithaca, New York, USA
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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5
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Bijelić L, Ruiz-Zepeda F, Hodnik N. The role of high-resolution transmission electron microscopy and aberration corrected scanning transmission electron microscopy in unraveling the structure-property relationships of Pt-based fuel cells electrocatalysts. Inorg Chem Front 2024; 11:323-341. [PMID: 38235274 PMCID: PMC10790562 DOI: 10.1039/d3qi01998e] [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: 09/29/2023] [Accepted: 12/05/2023] [Indexed: 01/19/2024]
Abstract
Platinum-based fuel cell electrocatalysts are structured on a nano level in order to extend their active surface area and maximize the utilization of precious and scarce platinum. Their performance is dictated by the atomic arrangement of their surface layers atoms via structure-property relationships. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) are the preferred methods for characterizing these catalysts, due to their capacity to achieve local atomic-level resolutions. Size, morphology, strain and local composition are just some of the properties of Pt-based nanostructures that can be obtained by (S)TEM. Furthermore, advanced methods of (S)TEM are able to provide insights into the quasi-in situ, in situ or even operando stability of these nanostructures. In this review, we present state-of-the-art applications of (S)TEM in the investigation and interpretation of structure-activity and structure-stability relationships.
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Affiliation(s)
- Lazar Bijelić
- Laboratory for Electrocatalysis, Department of Materials Chemistry, National Insititute of Chemistry Hajdrihova 19 1000 Ljubljana Slovenia
- University of Nova Gorica Vipavska 13 Nova Gorica SI-5000 Slovenia
| | - Francisco Ruiz-Zepeda
- Laboratory for Electrocatalysis, Department of Materials Chemistry, National Insititute of Chemistry Hajdrihova 19 1000 Ljubljana Slovenia
- Department of Physics and Chemistry of Materials, Institute for Metals and Technology IMT Lepi pot 11 1000 Ljubljana Slovenia
| | - Nejc Hodnik
- Laboratory for Electrocatalysis, Department of Materials Chemistry, National Insititute of Chemistry Hajdrihova 19 1000 Ljubljana Slovenia
- University of Nova Gorica Vipavska 13 Nova Gorica SI-5000 Slovenia
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6
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Moradifar P, Liu Y, Shi J, Siukola Thurston ML, Utzat H, van Driel TB, Lindenberg AM, Dionne JA. Accelerating Quantum Materials Development with Advances in Transmission Electron Microscopy. Chem Rev 2023. [PMID: 37979189 DOI: 10.1021/acs.chemrev.2c00917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2023]
Abstract
Quantum materials are driving a technology revolution in sensing, communication, and computing, while simultaneously testing many core theories of the past century. Materials such as topological insulators, complex oxides, superconductors, quantum dots, color center-hosting semiconductors, and other types of strongly correlated materials can exhibit exotic properties such as edge conductivity, multiferroicity, magnetoresistance, superconductivity, single photon emission, and optical-spin locking. These emergent properties arise and depend strongly on the material's detailed atomic-scale structure, including atomic defects, dopants, and lattice stacking. In this review, we describe how progress in the field of electron microscopy (EM), including in situ and in operando EM, can accelerate advances in quantum materials and quantum excitations. We begin by describing fundamental EM principles and operation modes. We then discuss various EM methods such as (i) EM spectroscopies, including electron energy loss spectroscopy (EELS), cathodoluminescence (CL), and electron energy gain spectroscopy (EEGS); (ii) four-dimensional scanning transmission electron microscopy (4D-STEM); (iii) dynamic and ultrafast EM (UEM); (iv) complementary ultrafast spectroscopies (UED, XFEL); and (v) atomic electron tomography (AET). We describe how these methods could inform structure-function relations in quantum materials down to the picometer scale and femtosecond time resolution, and how they enable precision positioning of atomic defects and high-resolution manipulation of quantum materials. For each method, we also describe existing limitations to solve open quantum mechanical questions, and how they might be addressed to accelerate progress. Among numerous notable results, our review highlights how EM is enabling identification of the 3D structure of quantum defects; measuring reversible and metastable dynamics of quantum excitations; mapping exciton states and single photon emission; measuring nanoscale thermal transport and coupled excitation dynamics; and measuring the internal electric field and charge density distribution of quantum heterointerfaces- all at the quantum materials' intrinsic atomic and near atomic-length scale. We conclude by describing open challenges for the future, including achieving stable sample holders for ultralow temperature (below 10K) atomic-scale spatial resolution, stable spectrometers that enable meV energy resolution, and high-resolution, dynamic mapping of magnetic and spin fields. With atomic manipulation and ultrafast characterization enabled by EM, quantum materials will be poised to integrate into many of the sustainable and energy-efficient technologies needed for the 21st century.
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Affiliation(s)
- Parivash Moradifar
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Yin Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jiaojian Shi
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road MS69, Menlo Park, California 94025, United States
| | | | - Hendrik Utzat
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aaron M Lindenberg
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road MS69, Menlo Park, California 94025, United States
| | - Jennifer A Dionne
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Radiology, Stanford University, Stanford, California 94305, United States
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7
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Pattison AJ, Pedroso CCS, Cohen BE, Ondry JC, Alivisatos AP, Theis W, Ercius P. Advanced techniques in automated high-resolution scanning transmission electron microscopy. NANOTECHNOLOGY 2023; 35:015710. [PMID: 37703845 DOI: 10.1088/1361-6528/acf938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 09/12/2023] [Indexed: 09/15/2023]
Abstract
Scanning transmission electron microscopy is a common tool used to study the atomic structure of materials. It is an inherently multimodal tool allowing for the simultaneous acquisition of multiple information channels. Despite its versatility, however, experimental workflows currently rely heavily on experienced human operators and can only acquire data from small regions of a sample at a time. Here, we demonstrate a flexible pipeline-based system for high-throughput acquisition of atomic-resolution structural data using an all-piezo sample stage applied to large-scale imaging of nanoparticles and multimodal data acquisition. The system is available as part of the user program of the Molecular Foundry at Lawrence Berkeley National Laboratory.
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Affiliation(s)
- Alexander J Pattison
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, United States of America
| | - Cassio C S Pedroso
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, United States of America
| | - Bruce E Cohen
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, United States of America
- Division of Molecular Biophysics & Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America
| | - Justin C Ondry
- Department of Chemistry, University of California, Berkeley, CA, United States of America
- Kavli Energy NanoScience Institute, Berkeley, CA, United States of America
- Department of Chemistry and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, United States of America
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, CA, United States of America
- Kavli Energy NanoScience Institute, Berkeley, CA, United States of America
- Department of Chemistry and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, United States of America
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
- Department of Materials Science and Engineering, University of California, Berkeley, CA, United States of America
| | - Wolfgang Theis
- School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Peter Ercius
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, United States of America
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8
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Kryvyi S, Kret S, Domagala JZ, Wojnar P. Reconstruction of three-dimensional strain field in an asymmetrical curved core-shell hetero-nanowire. NANOTECHNOLOGY 2023; 34:445705. [PMID: 37524071 DOI: 10.1088/1361-6528/acebf6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 07/31/2023] [Indexed: 08/02/2023]
Abstract
Crystal orientation and strain mapping of an individual curved and asymmetrical core-shell hetero-nanowire (NW) is performed based on transmission electron microscopy. It relies on a comprehensive analysis of scanning nanobeam electron diffraction data obtained for 1.3 nm electron probe size. The proposed approach also handles the problem of appearing twinning defects on diffraction patterns and allows for the investigation of materials with high defect densities. Based on the experimental maps and their comparison with finite element simulations, the entire core-shell geometry including full three-dimensional strain distribution within the curved core-shell NW are obtained. Our approach represents, therefore, a low-dose quasi-tomography of the strain field within a nanoobject using only a single zone axis diffraction experiment. Our approach is applicable also for electron beam-sensitive materials for which performing conventional tomography is a difficult task.
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Affiliation(s)
- Serhii Kryvyi
- Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Slawomir Kret
- Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Jaroslaw Z Domagala
- Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Piotr Wojnar
- Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw, Poland
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9
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Yoo T, Hershkovitz E, Pu X, He L, Kim H. Conjoining Simple Supervised and Unsupervised Machine Learning Methods with 4D-STEM to Identify Complex Nanostructures. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1959-1960. [PMID: 37612942 DOI: 10.1093/micmic/ozad067.1015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Timothy Yoo
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA
| | - Eitan Hershkovitz
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA
| | - Xiaofei Pu
- Advanced Characterization and PIE Division, Idaho National Laboratory, Idaho Falls, ID, USA
| | - Lingfeng He
- Department of Nuclear Engineering, North Carolina State University, Raleigh, NC, USA
| | - Honggyu Kim
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA
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10
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Zeltmann SE, Hsu SL, Brown HG, Susarla S, Ramesh R, Minor AM, Ophus C. Uncovering polar vortex structures by inversion of multiple scattering with a stacked Bloch wave model. Ultramicroscopy 2023; 250:113732. [PMID: 37087909 DOI: 10.1016/j.ultramic.2023.113732] [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: 11/10/2022] [Revised: 03/21/2023] [Accepted: 04/03/2023] [Indexed: 04/25/2023]
Abstract
Nanobeam electron diffraction can probe local structural properties of complex crystalline materials including phase, orientation, tilt, strain, and polarization. Ideally, each diffraction pattern from a projected area of a few unit cells would produce a clear Bragg diffraction pattern, where the reciprocal lattice vectors can be measured from the spacing of the diffracted spots, and the spot intensities are equal to the square of the structure factor amplitudes. However, many samples are too thick for this simple interpretation of their diffraction patterns, as multiple scattering of the electron beam can produce a highly nonlinear relationship between the spot intensities and the underlying structure. Here, we develop a stacked Bloch wave method to model the diffracted intensities from thick samples with structure that varies along the electron beam. Our method reduces the large parameter space of electron scattering to just a few structural variables per probe position, making it fast enough to apply to very large fields of view. We apply our method to SrTiO3/PbTiO3/SrTiO3 multilayer samples, and successfully disentangle specimen tilt from the mean polarization of the PbTiO3 layers. We elucidate the structure of complex vortex topologies in the PbTiO3 layers, demonstrating the promise of our method to extract material properties from thick samples.
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Affiliation(s)
- Steven E Zeltmann
- Department of Materials Science and Engineering, University of California, Berkeley, CA, United States of America.
| | - Shang-Lin Hsu
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | - Hamish G Brown
- Ian Holmes Imaging Centre, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria, Australia
| | - Sandhya Susarla
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, United States of America
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, United States of America
| | - Andrew M Minor
- Department of Materials Science and Engineering, University of California, Berkeley, CA, United States of America; National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America.
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11
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Bruefach A, Ophus C, Scott MC. Analysis of Interpretable Data Representations for 4D-STEM Using Unsupervised Learning. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-11. [PMID: 36073035 DOI: 10.1017/s1431927622012259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Understanding the structure of materials is crucial for engineering devices and materials with enhanced performance. Four-dimensional scanning transmission electron microscopy (4D-STEM) is capable of mapping nanometer-scale local crystallographic structure over micron-scale field of views. However, 4D-STEM datasets can contain tens of thousands of images from a wide variety of material structures, making it difficult to automate detection and classification of structures. Traditional automated analysis pipelines for 4D-STEM focus on supervised approaches, which require prior knowledge of the material structure and cannot describe anomalous or deviant structures. In this article, a pipeline for engineering 4D-STEM feature representations for unsupervised clustering using non-negative matrix factorization (NMF) is introduced. Each feature is evaluated using NMF and results are presented for both simulated and experimental data. It is shown that some data representations more reliably identify overlapping grains. Additionally, real space refinement is applied to identify spatially distinct sample regions, allowing for size and shape analysis to be performed. This work lays the foundation for improved analysis of nanoscale structural features in materials that deviate from expected crystallographic arrangement using 4D-STEM.
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Affiliation(s)
- Alexandra Bruefach
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Mary C Scott
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
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