1
|
Del-Pozo-Bueno D, Kepaptsoglou D, Ramasse QM, Peiró F, Estradé S. Machine Learning Data Augmentation Strategy for Electron Energy Loss Spectroscopy: Generative Adversarial Networks. Microsc Microanal 2024; 30:278-293. [PMID: 38684097 DOI: 10.1093/mam/ozae014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 08/01/2023] [Accepted: 02/12/2024] [Indexed: 05/02/2024]
Abstract
Recent advances in machine learning (ML) have highlighted a novel challenge concerning the quality and quantity of data required to effectively train algorithms in supervised ML procedures. This article introduces a data augmentation (DA) strategy for electron energy loss spectroscopy (EELS) data, employing generative adversarial networks (GANs). We present an innovative approach, called the data augmentation generative adversarial network (DAG), which facilitates data generation from a very limited number of spectra, around 100. Throughout this study, we explore the optimal configuration for GANs to produce realistic spectra. Notably, our DAG generates realistic spectra, and the spectra produced by the generator are successfully used in real-world applications to train classifiers based on artificial neural networks (ANNs) and support vector machines (SVMs) that have been successful in classifying experimental EEL spectra.
Collapse
Affiliation(s)
- Daniel Del-Pozo-Bueno
- LENS-MIND, Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, 1-11 Martí i Franquès, 08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, 1-11 Martí i Franquès, 08028 Barcelona, Spain
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, Sci-Tech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK
- School of Physics, Engineering and Technology, University of York, Newton way, YO10 5DD Heslington, UK
| | - Quentin M Ramasse
- SuperSTEM Laboratory, Sci-Tech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK
- Schools of Chemical and Process Engineering & Physics and Astronomy, Woodhouse Lane, University of Leeds, LS2 9JT Leeds, UK
| | - Francesca Peiró
- LENS-MIND, Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, 1-11 Martí i Franquès, 08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, 1-11 Martí i Franquès, 08028 Barcelona, Spain
| | - Sònia Estradé
- LENS-MIND, Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, 1-11 Martí i Franquès, 08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, 1-11 Martí i Franquès, 08028 Barcelona, Spain
| |
Collapse
|
2
|
Boukouvala C, West CA, Ten A, Hopper E, Ramasse QM, Biggins JS, Ringe E. Far-field, near-field and photothermal response of plasmonic twinned magnesium nanostructures. Nanoscale 2024; 16:7480-7492. [PMID: 38344779 PMCID: PMC11025716 DOI: 10.1039/d3nr05848d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 01/22/2024] [Indexed: 02/16/2024]
Abstract
Magnesium nanoparticles offer an alternative plasmonic platform capable of resonances across the ultraviolet, visible and near-infrared. Crystalline magnesium nanoparticles display twinning on the (101̄1), (101̄2), (101̄3), and (112̄1) planes leading to concave folded shapes named tents, chairs, tacos, and kites, respectively. We use the Wulff-based Crystal Creator tool to expand the range of Mg crystal shapes with twinning over the known Mg twin planes, i.e., (101̄x), x = 1, 2, 3 and (112̄y), y = 1, 2, 3, 4, and study the effects of relative facet expression on the resulting shapes. These shapes include both concave and convex structures, some of which have been experimentally observed. The resonant modes, far-field, and near-field optical responses of these unusual plasmonic shapes as well as their photothermal behaviour are reported, revealing the effects of folding angle and in-filling of the concave region. Significant differences exist between shapes, in particular regarding the maximum and average electric field enhancement. A maximum field enhancement (|E|/|E0|) of 184, comparable to that calculated for Au and Ag nanoparticles, was found at the tips of the (112̄4) kite. The presence of a 5 nm MgO shell is found to decrease the near-field enhancement by 67% to 90% depending on the shape, while it can increase the plasmon-induced temperature rise by up to 42%. Tip rounding on the otherwise sharp nanoparticle corners also significantly affects the maximum field enhancement. These results provide guidance for the design of enhancing and photothermal substrates for a variety of plasmonic applications across a wide spectral range.
Collapse
Affiliation(s)
- Christina Boukouvala
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
- Department of Earth Sciences, Downing Street, Cambridge, CB2 3EQ, UK
| | - Claire A West
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
- Department of Earth Sciences, Downing Street, Cambridge, CB2 3EQ, UK
| | - Andrey Ten
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
- Department of Earth Sciences, Downing Street, Cambridge, CB2 3EQ, UK
| | - Elizabeth Hopper
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
- Department of Earth Sciences, Downing Street, Cambridge, CB2 3EQ, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - Quentin M Ramasse
- School of Chemical and Process Engineering, University of Leeds, 211 Clarendon Road, Leeds, LS2 9JT, UK
- School of Physics and Astronomy, University of Leeds, Woodhouse, Leeds, LS2 9JS, UK
- SuperSTEM, SciTech Daresbury Science and Innovation Campus, Keckwick Lane, Warrington, WA4 4AD, UK
| | - John S Biggins
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK
| | - Emilie Ringe
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
- Department of Earth Sciences, Downing Street, Cambridge, CB2 3EQ, UK
| |
Collapse
|
3
|
Cardillo-Zallo I, Biskupek J, Bloodworth S, Marsden ES, Fay MW, Ramasse QM, Rance GA, Stoppiello CT, Cull WJ, Weare BL, Whitby RJ, Kaiser U, Brown PD, Khlobystov AN. Atomic-Scale Time-Resolved Imaging of Krypton Dimers, Chains and Transition to a One-Dimensional Gas. ACS Nano 2024; 18:2958-2971. [PMID: 38251654 PMCID: PMC10832048 DOI: 10.1021/acsnano.3c07853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/19/2023] [Accepted: 01/02/2024] [Indexed: 01/23/2024]
Abstract
Single-atom dynamics of noble-gas elements have been investigated using time-resolved transmission electron microscopy (TEM), with direct observation providing for a deeper understanding of chemical bonding, reactivity, and states of matter at the nanoscale. We report on a nanoscale system consisting of endohedral fullerenes encapsulated within single-walled carbon nanotubes ((Kr@C60)@SWCNT), capable of the delivery and release of krypton atoms on-demand, via coalescence of host fullerene cages under the action of the electron beam (in situ) or heat (ex situ). The state and dynamics of Kr atoms were investigated by energy dispersive X-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS). Kr atom positions were measured precisely using aberration-corrected high-resolution TEM (AC-HRTEM), aberration-corrected scanning TEM (AC-STEM), and single-atom spectroscopic imaging (STEM-EELS). The electron beam drove the formation of 2Kr@C120 capsules, in which van der Waals Kr2 and transient covalent [Kr2]+ bonding states were identified. Thermal coalescence led to the formation of longer coalesced nested nanotubes containing more loosely bound Krn chains (n = 3-6). In some instances, delocalization of Kr atomic positions was confirmed by STEM analysis as the transition to a one-dimensional (1D) gas, as Kr atoms were constrained to only one degree of translational freedom within long, well-annealed, nested nanotubes. Such nested nanotube structures were investigated by Raman spectroscopy. This material represents a highly compressed and dimensionally constrained 1D gas stable under ambient conditions. Direct atomic-scale imaging has revealed elusive bonding states and a previously unseen 1D gaseous state of matter of this noble gas element, demonstrating TEM to be a powerful tool in the discovery of chemistry at the single-atom level.
Collapse
Affiliation(s)
- Ian Cardillo-Zallo
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Johannes Biskupek
- Electron
Microscopy Group of Materials Science, Central Facility for Electron
Microscopy, Ulm University, Ulm 89081, Germany
| | - Sally Bloodworth
- School
of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Elizabeth S. Marsden
- School
of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Michael W. Fay
- Nanoscale
and Microscale Research Centre, University
of Nottingham, Nottingham NG7 2QL, United
Kingdom
| | - Quentin M. Ramasse
- SuperSTEM
Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- School of
Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Graham A. Rance
- Nanoscale
and Microscale Research Centre, University
of Nottingham, Nottingham NG7 2QL, United
Kingdom
| | - Craig T. Stoppiello
- Centre
for Microscopy and Microanalysis, The University
of Queensland, Brisbane, Queensland 4072, Australia
| | - William J. Cull
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Benjamin L. Weare
- Nanoscale
and Microscale Research Centre, University
of Nottingham, Nottingham NG7 2QL, United
Kingdom
| | - Richard J. Whitby
- School
of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Ute Kaiser
- Electron
Microscopy Group of Materials Science, Central Facility for Electron
Microscopy, Ulm University, Ulm 89081, Germany
| | - Paul D. Brown
- Department
of Mechanical, Materials & Manufacturing Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Andrei N. Khlobystov
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| |
Collapse
|
4
|
Vollmer C, Kepaptsoglou D, Leitner J, Mosberg AB, El Hajraoui K, King AJ, Bays CL, Schofield PF, Araki T, Ramasse QM. High-spatial resolution functional chemistry of nitrogen compounds in the observed UK meteorite fall Winchcombe. Nat Commun 2024; 15:778. [PMID: 38278803 PMCID: PMC10817942 DOI: 10.1038/s41467-024-45064-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 01/11/2024] [Indexed: 01/28/2024] Open
Abstract
Organic matter in extraterrestrial samples is a complex material that might have played an important role in the delivery of prebiotic molecules to the early Earth. We report here on the identification of nitrogen-containing compounds such as amino acids and N-heterocycles within the recent observed meteorite fall Winchcombe by high-spatial resolution spectroscopy techniques. Although nitrogen contents of Winchcombe organic matter are low (N/C ~ 1-3%), we were able to detect the presence of these compounds using a low-noise direct electron detector. These biologically relevant molecules have therefore been tentatively found within a fresh, minimally processed meteorite sample by high spatial resolution techniques conserving the overall petrographic context. Carbon functional chemistry investigations show that sizes of aromatic domains are small and that abundances of carboxylic functional groups are low. Our observations demonstrate that Winchcombe represents an important addition to the collection of carbonaceous chondrites and still preserves pristine extraterrestrial organic matter.
Collapse
Affiliation(s)
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, Keckwick Lane, Daresbury, UK
- School of Physics, Engineering and Technology, University of York, Heslington, UK
| | - Jan Leitner
- Institut für Geowissenschaften, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
- Max Planck Institute for Chemistry, Particle Chemistry Department, Mainz, Germany
| | | | - Khalil El Hajraoui
- SuperSTEM Laboratory, Keckwick Lane, Daresbury, UK
- School of Physics, Engineering and Technology, University of York, Heslington, UK
| | - Ashley J King
- Planetary Materials Group, Natural History Museum, London, UK
| | - Charlotte L Bays
- Planetary Materials Group, Natural History Museum, London, UK
- Department of Earth Sciences, Royal Holloway, University of London, Egham, UK
| | | | - Tohru Araki
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
- National Institutes of Natural Sciences, Institute for Molecular Science, UVSOR Synchrotron Facility, Okazaki, Japan
| | - Quentin M Ramasse
- SuperSTEM Laboratory, Keckwick Lane, Daresbury, UK
- School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds, UK
| |
Collapse
|
5
|
Ten A, West CA, Jeong S, Hopper ER, Wang Y, Zhu B, Ramasse QM, Ye X, Ringe E. Bimetallic copper palladium nanorods: plasmonic properties and palladium content effects. Nanoscale Adv 2023; 5:6524-6532. [PMID: 38024297 PMCID: PMC10662198 DOI: 10.1039/d3na00523b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023]
Abstract
Cu is an inexpensive alternative plasmonic metal with optical behaviour comparable to Au but with much poorer environmental stability. Alloying with a more stable metal can improve stability and add functionality, with potential effects on the plasmonic properties. Here we investigate the plasmonic behaviour of Cu nanorods and Cu-CuPd nanorods containing up to 46 mass percent Pd. Monochromated scanning transmission electron microscopy electron energy-loss spectroscopy first reveals the strong length dependence of multiple plasmonic modes in Cu nanorods, where the plasmon peaks redshift and narrow with increasing length. Next, we observe an increased damping (and increased linewidth) with increasing Pd content, accompanied by minimal frequency shift. These results are corroborated by and expanded upon with numerical simulations using the electron-driven discrete dipole approximation. This study indicates that adding Pd to nanostructures of Cu is a promising method to expand the scope of their plasmonic applications.
Collapse
Affiliation(s)
- Andrey Ten
- Department of Materials Science and Metallurgy, University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK
- Department of Earth Sciences, University of Cambridge Downing Street Cambridge CB2 3EQ UK
| | - Claire A West
- Department of Materials Science and Metallurgy, University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK
- Department of Earth Sciences, University of Cambridge Downing Street Cambridge CB2 3EQ UK
| | - Soojin Jeong
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington Indiana 47405 USA
| | - Elizabeth R Hopper
- Department of Materials Science and Metallurgy, University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK
- Department of Earth Sciences, University of Cambridge Downing Street Cambridge CB2 3EQ UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge Philippa Fawcett Drive Cambridge CB3 0AS UK
| | - Yi Wang
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington Indiana 47405 USA
| | - Baixu Zhu
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington Indiana 47405 USA
| | - Quentin M Ramasse
- School of Chemical and Process Engineering, University of Leeds Leeds LS2 9JT UK
- School of Physics and Astronomy, University of Leeds Leeds LS2 9JS UK
- SuperSTEM, SciTech Daresbury Science and Innovation Campus Keckwick Lane Daresbury WA4 4AD UK
| | - Xingchen Ye
- Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington Indiana 47405 USA
| | - Emilie Ringe
- Department of Materials Science and Metallurgy, University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK
- Department of Earth Sciences, University of Cambridge Downing Street Cambridge CB2 3EQ UK
| |
Collapse
|
6
|
Castellanos-Reyes JÁ, Zeiger P, Bergman A, Kepaptsoglou D, Ramasse QM, Idrobo JC, Rusz J. Simulations of Magnon Diffuse Scattering in bcc Fe: The Impact of Temperature on Magnon Detection in STEM. Microsc Microanal 2023; 29:646. [PMID: 37613290 DOI: 10.1093/micmic/ozad067.316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
| | - Paul Zeiger
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Anders Bergman
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, United Kingdom
- Department of Physics, University of York, York, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, United Kingdom
- School of Chemical and Process Engineering, University of Leeds, Leeds, United Kingdom
- School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom
| | - Juan Carlos Idrobo
- Materials Science and Engineering Department, University of Washington, Seattle, Washington, USA
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| |
Collapse
|
7
|
Fung KLY, Skowron ST, Hayter R, Mason SE, Weare BL, Besley NA, Ramasse QM, Allen CS, Khlobystov AN. Direct measurement of single-molecule dynamics and reaction kinetics in confinement using time-resolved transmission electron microscopy. Phys Chem Chem Phys 2023; 25:9092-9103. [PMID: 36920796 DOI: 10.1039/d2cp05183d] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
We report experimental methodologies utilising transmission electron microscopy (TEM) as an imaging tool for reaction kinetics at the single molecule level, in direct space and with spatiotemporal continuity. Using reactions of perchlorocoronene (PCC) in nanotubes of different diameters and at different temperatures, we found a period of molecular movement to precede the intermolecular addition of PCC, with a stronger dependence of the reaction rate on the nanotube diameter, controlling the local environments around molecules, than on the reaction temperature (-175, 23 or 400 °C). Once initiated, polymerisation of PCC follows zero-order reaction kinetics with the observed reaction cross section σobs of 1.13 × 10-9 nm2 (11.3 ± 0.6 barn), determined directly from time-resolved TEM image series acquired with a rate of 100 frames per second. Polymerisation was shown to proceed from a single point, with molecules reacting sequentially, as in a domino effect, due to the strict conformational requirement of the Diels-Alder cycloaddition creating the bottleneck for the reaction. The reaction mechanism was corroborated by correlating structures of reaction intermediates observed in TEM images, with molecular weights measured by using mass spectrometry (MS) when the same reaction was triggered by UV irradiation. The approaches developed in this study bring the imaging of chemical reactions at the single-molecule level closer to traditional concepts of chemistry.
Collapse
Affiliation(s)
- Kayleigh L Y Fung
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Stephen T Skowron
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Ruth Hayter
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Stephen E Mason
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Benjamin L Weare
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Nicholas A Besley
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK.,School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Christopher S Allen
- Electron Physical Sciences Imaging Centre, Diamond Light Source Ltd., Oxfordshire OX11 0DE, UK.,Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Andrei N Khlobystov
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| |
Collapse
|
8
|
Sokolikova MS, Cheng G, Och M, Palczynski P, El Hajraoui K, Ramasse QM, Mattevi C. Tuning the 1T'/2H phases in W xMo 1-xSe 2 nanosheets. Nanoscale 2023; 15:2714-2725. [PMID: 36651927 PMCID: PMC9909680 DOI: 10.1039/d2nr05631c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Controlling materials' morphology, crystal phase and chemical composition at the atomic scale has become central in materials research. Wet chemistry approaches have great potential in directing the material crystallisation process to achieve tuneable chemical compositions as well as to target specific crystal phases. Herein, we report the compositional and crystal phase tuneability achieved in the quasi-binary WxMo1-xSe2 system with chemical and crystal phase mixing down to the atomic level. A series of WxMo1-xSe2 solid solutions in the form of nanoflowers with atomically thin petals were obtained via a direct colloidal reaction by systematically varying the ratios of transition metal precursors. We investigate the effect of selenium precursor on the morphology of the WxMo1-xSe2 material and show how using elemental selenium can enable the formation of larger and distinct nanoflowers. While the synthesised materials are compositionally homogeneous, they exhibit crystal phase heterogeneity with the co-existing domains of the 1T' and 2H crystal phases, and with evidence of MoSe2 in the metastable 1T' phase. We show at single atom level of resolution, that tungsten and molybdenum can be found in both the 1T' and 2H lattices. The formation of heterophase 1T'/2H WxMo1-xSe2 electrocatalysts allowed for a considerable improvement in the activity for the acidic hydrogen evolution reaction (HER) compared to pristine, 1T'-dominated, WSe2. This work can pave the way towards engineered functional nanomaterials where properties, such as electronic and catalytic, have to be controlled at the atomic scale.
Collapse
Affiliation(s)
| | - Gang Cheng
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
| | - Mauro Och
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
| | - Pawel Palczynski
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
| | - Khalil El Hajraoui
- SuperSTEM Laboratory, SciTech Daresbury, Keckwick Lane, Daresbury WA4 4AD, UK
- York NanoCentre & Department of Physics, University of York, York YO10 5DD, UK
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury, Keckwick Lane, Daresbury WA4 4AD, UK
- School of Physics and Astronomy & School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - Cecilia Mattevi
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
| |
Collapse
|
9
|
Liu X, Kepaptsoglou D, Jakubczyk E, Yu J, Thomas A, Wang B, Azough F, Gao Z, Zhong X, Dorey R, Ramasse QM, Freer R. High Power Factor Nb-Doped TiO 2 Thermoelectric Thick Films: Toward Atomic Scale Defect Engineering of Crystallographic Shear Structures. ACS Appl Mater Interfaces 2023; 15:5071-5085. [PMID: 36656149 PMCID: PMC9906629 DOI: 10.1021/acsami.2c16587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
Donor-doped TiO2-based materials are promising thermoelectrics (TEs) due to their low cost and high stability at elevated temperatures. Herein, high-performance Nb-doped TiO2 thick films are fabricated by facile and scalable screen-printing techniques. Enhanced TE performance has been achieved by forming high-density crystallographic shear (CS) structures. All films exhibit the same matrix rutile structure but contain different nano-sized defect structures. Typically, in films with low Nb content, high concentrations of oxygen-deficient {121} CS planes are formed, while in films with high Nb content, a high density of twin boundaries are found. Through the use of strongly reducing atmospheres, a novel Al-segregated {210} CS structure is formed in films with higher Nb content. By advanced aberration-corrected scanning transmission electron microscopy techniques, we reveal the nature of the {210} CS structure at the nano-scale. These CS structures contain abundant oxygen vacancies and are believed to enable energy-filtering effects, leading to simultaneous enhancement of both the electrical conductivity and Seebeck coefficients. The optimized films exhibit a maximum power factor of 4.3 × 10-4 W m-1 K-2 at 673 K, the highest value for TiO2-based TE films at elevated temperatures. Our modulation strategy based on microstructure modification provides a novel route for atomic-level defect engineering which should guide the development of other TE materials.
Collapse
Affiliation(s)
- Xiaodong Liu
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
| | - Demie Kepaptsoglou
- SuperSTEM
Laboratory, STFC Daresbury
Campus, DaresburyWA4 4AD, U.K.
- Department
of Physics, University of York, YorkYO10 5DD, U.K.
| | - Ewa Jakubczyk
- School
of Mechanical Engineering Sciences, University
of Surrey, Guildford, Surrey GU2 7XH, U.K.
| | - Jincheng Yu
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
| | - Andrew Thomas
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
- Photon
Science Institute, University of Manchester, ManchesterM13 9PL, U.K.
- Henry Royce
Institute, University of Manchester, ManchesterM13 9PL, U.K.
| | - Bing Wang
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
| | - Feridoon Azough
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
| | - Zhaohe Gao
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
| | - Xiangli Zhong
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
- Photon
Science Institute, University of Manchester, ManchesterM13 9PL, U.K.
| | - Robert Dorey
- School
of Mechanical Engineering Sciences, University
of Surrey, Guildford, Surrey GU2 7XH, U.K.
| | - Quentin M. Ramasse
- SuperSTEM
Laboratory, STFC Daresbury
Campus, DaresburyWA4 4AD, U.K.
- School
of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, LeedsLS2 9JT, U.K.
| | - Robert Freer
- Department
of Materials, University of Manchester, ManchesterM13 9PL, U.K.
| |
Collapse
|
10
|
Lawrence RA, Ramasse QM, Holsgrove KM, Sando D, Cazorla C, Valanoor N, Arredondo MA. Effects of Multiple Local Environments on Electron Energy Loss Spectra of Epitaxial Perovskite Interfaces. J Phys Chem C Nanomater Interfaces 2022; 126:21453-21466. [PMID: 36582487 PMCID: PMC9791663 DOI: 10.1021/acs.jpcc.2c06879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/15/2022] [Indexed: 06/17/2023]
Abstract
The role of local chemical environments in the electron energy loss spectra of complex multiferroic oxides was studied using computational and experimental techniques. The evolution of the O K-edge across an interface between bismuth ferrite (BFO) and lanthanum strontium manganate (LSMO) was considered through spectral averaging over crystallographically equivalent positions to capture the periodicity of the local O environments. Computational techniques were used to investigate the contribution of individual atomic environments to the overall spectrum, and the role of doping and strain was considered. Chemical variation, even at the low level, was found to have a major impact on the spectral features, whereas strain only induced a small chemical shift to the edge onset energy. Through a combination of these methods, it was possible to explain experimentally observed effects such as spectral flattening near the interface as the combination of spectral responses from multiple local atomic environments.
Collapse
Affiliation(s)
- Robert A. Lawrence
- Department
of Physics, University of York, Heslington, North YorkshireYO10 5DD, United Kingdom
| | - Quentin M. Ramasse
- SuperSTEM
Laboratory, SciTech Daresbury Campus, DaresburyWA4 4AD, United Kingdom
- School
of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Kristina M. Holsgrove
- School
of Mathematics and Physics, Queen’s
University Belfast, BelfastBT7 1NN, Northern Ireland, United Kingdom
| | - Daniel Sando
- School
of Physical and Chemical Sciences, University
of Canterbury, ChristChurch8140, New Zealand
| | - Claudio Cazorla
- Departament
de Fisica, Universitat Politecnica de Catalunya, BarcelonaE-08034, Catalonia, Spain
| | - Nagarajan Valanoor
- School
of Materials Science and Engineering, University
of New South Wales, Sydney, NSW2052, Australia
| | - Miryam A. Arredondo
- School
of Mathematics and Physics, Queen’s
University Belfast, BelfastBT7 1NN, Northern Ireland, United Kingdom
| |
Collapse
|
11
|
Büchele S, Yakimov A, Collins SM, Ruiz-Ferrando A, Chen Z, Willinger E, Kepaptsoglou DM, Ramasse QM, Müller CR, Safonova OV, López N, Copéret C, Pérez-Ramírez J, Mitchell S. Elucidation of Metal Local Environments in Single-Atom Catalysts Based on Carbon Nitrides. Small 2022; 18:e2202080. [PMID: 35678101 DOI: 10.1002/smll.202202080] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 05/05/2022] [Indexed: 06/15/2023]
Abstract
The ability to tailor the properties of metal centers in single-atom heterogeneous catalysts depends on the availability of advanced approaches for characterization of their structure. Except for specific host materials with well-defined metal adsorption sites, determining the local atomic environment remains a crucial challenge, often relying heavily on simulations. This article reports an advanced analysis of platinum atoms stabilized on poly(triazine imide), a nanocrystalline form of carbon nitride. The approach discriminates the distribution of surface coordination sites in the host, the evolution of metal coordination at different stages during the synthesis of the material, and the potential locations of metal atoms within the lattice. Consistent with density functional theory predictions, simultaneous high-resolution imaging in high-angle annular dark field and bright field modes experimentally confirms the preferred localization of platinum in-plane in the corners of the triangular cavities. X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and dynamic nuclear polarization enhanced 15 N nuclear magnetic resonance (DNP-NMR) spectroscopies coupled with density functional theory (DFT) simulations reveal that the predominant metal species comprise Pt(II) bound to three nitrogen atoms and one chlorine atom inside the coordination sites. The findings, which narrow the gap between experimental and theoretical elucidation, contribute to the improved structural understanding and provide a benchmark for exploring the speciation of single-atom catalysts based on carbon nitrides.
Collapse
Affiliation(s)
- Simon Büchele
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, Zurich, 8093, Switzerland
| | - Alexander Yakimov
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, Zurich, 8093, Switzerland
| | - Sean M Collins
- Bragg Centre for Materials Research, School of Chemical and Process Engineering and School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Andrea Ruiz-Ferrando
- Institute of Chemical Research of Catalonia and Barcelona Institute of Science and Technology, Av. Països Catalans 16, Tarragona, 43007, Spain
| | - Zupeng Chen
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, P. R. China
| | - Elena Willinger
- Department of Mechanical and Process Engineering, ETH Zurich, Leonhardstrasse 21, Zurich, 8092, Switzerland
| | | | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, WA4 4AD, UK
| | - Christoph R Müller
- Department of Mechanical and Process Engineering, ETH Zurich, Leonhardstrasse 21, Zurich, 8092, Switzerland
| | - Olga V Safonova
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen, 5232, Switzerland
| | - Núria López
- Institute of Chemical Research of Catalonia and Barcelona Institute of Science and Technology, Av. Països Catalans 16, Tarragona, 43007, Spain
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, Zurich, 8093, Switzerland
| | - Javier Pérez-Ramírez
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, Zurich, 8093, Switzerland
| | - Sharon Mitchell
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, Zurich, 8093, Switzerland
| |
Collapse
|
12
|
Li Y, Zatterin E, Conroy M, Pylypets A, Borodavka F, Björling A, Groenendijk DJ, Lesne E, Clancy AJ, Hadjimichael M, Kepaptsoglou D, Ramasse QM, Caviglia AD, Hlinka J, Bangert U, Leake SJ, Zubko P. Electrostatically Driven Polarization Flop and Strain-Induced Curvature in Free-Standing Ferroelectric Superlattices. Adv Mater 2022; 34:e2106826. [PMID: 35064954 DOI: 10.1002/adma.202106826] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 12/21/2021] [Indexed: 06/14/2023]
Abstract
The combination of strain and electrostatic engineering in epitaxial heterostructures of ferroelectric oxides offers many possibilities for inducing new phases, complex polar topologies, and enhanced electrical properties. However, the dominant effect of substrate clamping can also limit the electromechanical response and often leaves electrostatics to play a secondary role. Releasing the mechanical constraint imposed by the substrate can not only dramatically alter the balance between elastic and electrostatic forces, enabling them to compete on par with each other, but also activates new mechanical degrees of freedom, such as the macroscopic curvature of the heterostructure. In this work, an electrostatically driven transition from a predominantly out-of-plane polarized to an in-plane polarized state is observed when a PbTiO3 /SrTiO3 superlattice with a SrRuO3 bottom electrode is released from its substrate. In turn, this polarization rotation modifies the lattice parameter mismatch between the superlattice and the thin SrRuO3 layer, causing the heterostructure to curl up into microtubes. Through a combination of synchrotron-based scanning X-ray diffraction imaging, Raman scattering, piezoresponse force microscopy, and scanning transmission electron microscopy, the crystalline structure and domain patterns of the curved superlattices are investigated, revealing a strong anisotropy in the domain structure and a complex mechanism for strain accommodation.
Collapse
Affiliation(s)
- Yaqi Li
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
| | - Edoardo Zatterin
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, Grenoble, 38000, France
| | - Michele Conroy
- Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
- Department of Physics, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland
- London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0HA, UK
| | - Anastasiia Pylypets
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Praha 8, Czech Republic
| | - Fedir Borodavka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Praha 8, Czech Republic
| | | | - Dirk J Groenendijk
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, Delft, GA 2600, The Netherlands
| | - Edouard Lesne
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, Delft, GA 2600, The Netherlands
| | - Adam J Clancy
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Marios Hadjimichael
- Department of Quantum Matter Physics, University of Geneva, Geneva, 1211, Switzerland
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, WA4 4AD, UK
- Department of Physics, University of York, York, YO10 5DD, UK
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, WA4 4AD, UK
- Schools of Chemical and Process Engineering, & Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Andrea D Caviglia
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, Delft, GA 2600, The Netherlands
| | - Jiri Hlinka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Praha 8, Czech Republic
| | - Ursel Bangert
- Department of Physics, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland
| | - Steven J Leake
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, Grenoble, 38000, France
| | - Pavlo Zubko
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
- London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0HA, UK
| |
Collapse
|
13
|
Mitchell S, Parés F, Faust Akl D, Collins SM, Kepaptsoglou DM, Ramasse QM, Garcia-Gasulla D, Pérez-Ramírez J, López N. Automated Image Analysis for Single-Atom Detection in Catalytic Materials by Transmission Electron Microscopy. J Am Chem Soc 2022; 144:8018-8029. [PMID: 35333043 DOI: 10.1021/jacs.1c12466] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Single-atom catalytic sites may have existed in all supported transition metal catalysts since their first application. Yet, interest in the design of single-atom heterogeneous catalysts (SACs) only really grew when advances in transmission electron microscopy (TEM) permitted direct confirmation of metal site isolation. While atomic-resolution imaging remains a central characterization tool, poor statistical significance, reproducibility, and interoperability limit its scope for deriving robust characteristics about these frontier catalytic materials. Here, we introduce a customized deep-learning method for automated atom detection in image analysis, a rate-limiting step toward high-throughput TEM. Platinum atoms stabilized on a functionalized carbon support with a challenging irregular three-dimensional morphology serve as a practically relevant test system with promising scope in thermo- and electrochemical applications. The model detects over 20,000 atomic positions for the statistical analysis of important properties for establishing structure-performance relations over nanostructured catalysts, like the surface density, proximity, clustering extent, and dispersion uniformity of supported metal species. Good performance obtained on direct application of the model to an iron SAC based on carbon nitride demonstrates its generalizability for single-atom detection on carbon-related materials. The approach establishes a route to integrate artificial intelligence into routine TEM workflows. It accelerates image processing times by orders of magnitude and reduces human bias by providing an uncertainty analysis that is not readily quantifiable in manual atom identification, improving standardization and scalability.
Collapse
Affiliation(s)
- Sharon Mitchell
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
| | - Ferran Parés
- Barcelona Supercomputing Center (BSC), Plaça d'Eusebi Güell 1-3, 08034 Barcelona, Spain
| | - Dario Faust Akl
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
| | - Sean M Collins
- School of Chemical and Process Engineering and School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Demie M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K.,Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K.,School of Chemical and Process Engineering and School of Physics, University of Leeds, Leeds LS2 9JT, U.K
| | - Dario Garcia-Gasulla
- Barcelona Supercomputing Center (BSC), Plaça d'Eusebi Güell 1-3, 08034 Barcelona, Spain
| | - Javier Pérez-Ramírez
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
| | - Núria López
- Institute of Chemical Research of Catalonia and The Barcelona Institute of Science and Technology, 43007 Tarragona, Spain
| |
Collapse
|
14
|
Bugnet M, Ederer M, Lazarov VK, Li L, Ramasse QM, Löffler S, Kepaptsoglou DM. Imaging the Spatial Distribution of Electronic States in Graphene Using Electron Energy-Loss Spectroscopy: Prospect of Orbital Mapping. Phys Rev Lett 2022; 128:116401. [PMID: 35363018 DOI: 10.1103/physrevlett.128.116401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 12/23/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
The spatial distributions of antibonding π^{*} and σ^{*} states in epitaxial graphene multilayers are mapped using electron energy-loss spectroscopy in a scanning transmission electron microscope. Inelastic channeling simulations validate the interpretation of the spatially resolved signals in terms of electronic orbitals, and demonstrate the crucial effect of the material thickness on the experimental capability to resolve the distribution of unoccupied states. This work illustrates the current potential of core-level electron energy-loss spectroscopy towards the direct visualization of electronic orbitals in a wide range of materials, of huge interest to better understand chemical bonding among many other properties at interfaces and defects in solids.
Collapse
Affiliation(s)
- M Bugnet
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
- Univ Lyon, CNRS, INSA Lyon, UCBL, MATEIS, UMR 5510, 69621 Villeurbanne, France
| | - M Ederer
- University Service Centre for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10/E057-02, 1040 Wien, Austria
| | - V K Lazarov
- Department of Physics, University of York, York YO10 5DD, United Kingdom
| | - L Li
- Department of Physics and Astronomy, University of West Virginia, Morgantown, West Virginia 26506, USA
| | - Q M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - S Löffler
- University Service Centre for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10/E057-02, 1040 Wien, Austria
| | - D M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- Department of Physics, University of York, York YO10 5DD, United Kingdom
| |
Collapse
|
15
|
Liu X, Kepaptsoglou D, Gao Z, Thomas A, Maji K, Guilmeau E, Azough F, Ramasse QM, Freer R. Controlling the Thermoelectric Properties of Nb-Doped TiO 2 Ceramics through Engineering Defect Structures. ACS Appl Mater Interfaces 2021; 13:57326-57340. [PMID: 34844406 DOI: 10.1021/acsami.1c18236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Donor-doped TiO2 ceramics are promising high-temperature oxide thermoelectrics. Highly dense (1 - x)TiO2-xNb2O5 (0.005 ≤ x ≤ 0.06) ceramics were prepared by a single-step, mixed-oxide route under reducing conditions. The microstructures contained polygonal-shaped grains with uniform grain size distributions. Subgrain structures were formed in samples with low Nb contents by the interlacing of rutile and higher-order Magnéli phases, reflecting the high density of shear planes and oxygen vacancies. Samples prepared with a higher Nb content showed no subgrain structures but high densities of planar defects and lower concentrations of oxygen vacancies. Through optimizing the concentration of point defects and line defects, the carrier concentration and electrical conductivity were enhanced, yielding a much improved power factor of 5.3 × 10-4 W m-1 K-2 at 823 K; lattice thermal conductivity was significantly reduced by enhanced phonon scattering. A low, temperature-stable thermal conductivity of 2.6 W m-1 K-1 was achieved, leading to a ZT value of 0.17 at 873 K for compositions with x = 0.06, the highest ZT value reported for single Nb-doped TiO2 ceramics without the use of spark plasma sintering (SPS). We demonstrate the control of the thermoelectric properties of Nb-doped TiO2 ceramics through the development of balanced defect structures, which could guide the development of future oxide thermoelectric materials.
Collapse
Affiliation(s)
- Xiaodong Liu
- Department of Materials, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury, Warrington WA4 4AD, United Kingdom
| | - Zhaohe Gao
- Department of Materials, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Andrew Thomas
- Department of Materials, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Krishnendu Maji
- CRISMAT, ENSICAEN, UNICAEN, Normandie Univ, CNRS, 14000 Caen, France
| | - Emmanuel Guilmeau
- CRISMAT, ENSICAEN, UNICAEN, Normandie Univ, CNRS, 14000 Caen, France
| | - Feridoon Azough
- Department of Materials, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury, Warrington WA4 4AD, United Kingdom
| | - Robert Freer
- Department of Materials, University of Manchester, Manchester M13 9PL, United Kingdom
| |
Collapse
|
16
|
Zamani RR, Hage FS, Eljarrat A, Namazi L, Ramasse QM, Dick KA. Unraveling electronic band structure of narrow-bandgap p-n nanojunctions in heterostructured nanowires. Phys Chem Chem Phys 2021; 23:25019-25023. [PMID: 34730587 DOI: 10.1039/d1cp03275e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electronic band structure of complex nanostructured semiconductors has a considerable effect on the final electronic and optical properties of the material and, ultimately, on the functionality of the devices incorporating them. Valence electron energy-loss spectroscopy (VEELS) in the transmission electron microscope (TEM) provides the possibility of measuring this property of semiconductors with high spatial resolution. However, it still represents a challenge for narrow-bandgap semiconductors, since an electron beam with low energy spread is required. Here we demonstrate that by means of monochromated VEELS we can study the electronic band structure of narrow-gap materials GaSb and InAs in the form of heterostructured nanowires, with bandgap values down to 0.5 eV, especially important for newly developed structures with unknown bandgaps. Using complex heterostructured InAs-GaSb nanowires, we determine a bandgap value of 0.54 eV for wurtzite InAs. Moreover, we directly compare the bandgaps of wurtzite and zinc blende polytypes of GaSb in a single nanostructure, measured here as 0.84 and 0.75 eV, respectively. This allows us to solve an existing controversy in the band alignment between these structures arising from theoretical predictions. The findings demonstrate the potential of monochromated VEELS to provide a better understanding of the band alignment at the heterointerfaces of narrow-bandgap complex nanostructured materials with high spatial resolution. This is especially important for semiconductor device applications where even the slightest variations of the electronic band structure at the nanoscale can play a crucial role in their functionality.
Collapse
Affiliation(s)
- Reza R Zamani
- Solid State Physics, Lund University, Box 118, Lund 22100, Sweden. .,Department of Physics, Chalmers University of Technology, Gothenburg 41296, Sweden
| | - Fredrik S Hage
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, UK.,Department of Materials, University of Oxford, Oxford OX1 3PH, UK.,Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, Oslo 0318, Norway
| | - Alberto Eljarrat
- Institute of Physics, Humboldt University of Berlin, Berlin 12489, Germany
| | - Luna Namazi
- Solid State Physics, Lund University, Box 118, Lund 22100, Sweden.
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, UK.,School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Kimberly A Dick
- Solid State Physics, Lund University, Box 118, Lund 22100, Sweden. .,Centre for Analysis and Synthesis, Lund University, Box 124, Lund 22100, Sweden
| |
Collapse
|
17
|
Huang H, Hayes ETC, Gianolio D, Cibin G, Hage FS, Ramasse QM, Russell AE. Role of SnO
2
in the Bifunctional Mechanism of CO Oxidation at Pt‐SnO
2
Electrocatalysts. ChemElectroChem 2021. [DOI: 10.1002/celc.202100642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Haoliang Huang
- School of Chemistry University of Southampton Highfield Southampton SO17 1BJ United Kingdom
| | - Edward T. C. Hayes
- School of Chemistry University of Southampton Highfield Southampton SO17 1BJ United Kingdom
| | - Diego Gianolio
- Diamond Light Source Ltd Diamond House Harwell Campus Didcot OX11 0DE United Kingdom
| | - Giannantonio Cibin
- Diamond Light Source Ltd Diamond House Harwell Campus Didcot OX11 0DE United Kingdom
| | - Fredrik S. Hage
- SuperSTEM Laboratory SciTech Daresbury Campus Daresbury WA4 4AD United Kingdom
- Department of Physics/Centre for Materials Science and Nanotechnology University of Oslo 0318 Oslo Norway
| | - Quentin M. Ramasse
- SuperSTEM Laboratory SciTech Daresbury Campus Daresbury WA4 4AD United Kingdom
- School of Physics and Astronomy School of Chemical and Process Engineering University of Leeds Leeds LS2 9JT United Kingdom
| | - Andrea E. Russell
- School of Chemistry University of Southampton Highfield Southampton SO17 1BJ United Kingdom
| |
Collapse
|
18
|
Moreno M, Arredondo M, Ramasse QM, McLaren M, Stötzner P, Förster S, Benavente E, Salgado C, Devis S, Solar P, Velasquez L, González G. Publisher Correction: ZnO nucleation into trititanate nanotubes by ALD equipment techniques, a new way to functionalize layered metal oxides. Sci Rep 2021; 11:12856. [PMID: 34127784 PMCID: PMC8203773 DOI: 10.1038/s41598-021-92227-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Mabel Moreno
- Universidad SEK, Instituto de investigación Interdisciplinar en Ciencias Biomédicas SEK (I3CBSEK), Facultad Ciencias de la Salud, Fernando Manterola 0789, Providencia, Santiago, Chile. .,Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany. .,Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Nuñoa, Santiago, Chile.
| | | | - Quentin M Ramasse
- SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury, WA4 4AD, UK.,School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Matthew McLaren
- Living Systems Institute, University of Exeter, Exeter, EX4 4QD, UK
| | | | - Stefan Förster
- Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - Eglantina Benavente
- Departamento de Química, Facultad de Ciencias Naturales, Matemática y Medio Ambiente, Universidad Tecnológica Metropolitana, Santiago, Chile.,Programa Institucional de Fomento a la Investigación, Desarrollo E Innovación (PIDi), Universidad Tecnológica Metropolitana, Santiago, Chile
| | - Caterina Salgado
- Departamento de Química, Facultad de Ciencias Naturales, Matemática y Medio Ambiente, Universidad Tecnológica Metropolitana, Santiago, Chile
| | - Sindy Devis
- Universidad SEK, Instituto de investigación Interdisciplinar en Ciencias Biomédicas SEK (I3CBSEK), Facultad Ciencias de la Salud, Fernando Manterola 0789, Providencia, Santiago, Chile
| | - Paula Solar
- Universidad SEK, Instituto de investigación Interdisciplinar en Ciencias Biomédicas SEK (I3CBSEK), Facultad Ciencias de la Salud, Fernando Manterola 0789, Providencia, Santiago, Chile
| | - Luis Velasquez
- Universidad SEK, Instituto de investigación Interdisciplinar en Ciencias Biomédicas SEK (I3CBSEK), Facultad Ciencias de la Salud, Fernando Manterola 0789, Providencia, Santiago, Chile
| | - Guillermo González
- Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Nuñoa, Santiago, Chile.
| |
Collapse
|
19
|
Vollmer C, Leitner J, Kepaptsoglou D, Ramasse QM, King AJ, Schofield PF, Bischoff A, Araki T, Hoppe P. A primordial 15N-depleted organic component detected within the carbonaceous chondrite Maribo. Sci Rep 2020; 10:20251. [PMID: 33219224 PMCID: PMC7679378 DOI: 10.1038/s41598-020-77190-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 11/06/2020] [Indexed: 11/09/2022] Open
Abstract
We report on the detection of primordial organic matter within the carbonaceous chondrite Maribo that is distinct from the majority of organics found in extraterrestrial samples. We have applied high-spatial resolution techniques to obtain C-N isotopic compositions, chemical, and structural information of this material. The organic matter is depleted in 15N relative to the terrestrial value at around δ15N ~ -200‰, close to compositions in the local interstellar medium. Morphological investigations by electron microscopy revealed that the material consists of µm- to sub-µm-sized diffuse particles dispersed within the meteorite matrix. Electron energy loss and synchrotron X-ray absorption near-edge structure spectroscopies show that the carbon functional chemistry is dominated by aromatic and C=O bonding environments similar to primordial organics from other carbonaceous chondrites. The nitrogen functional chemistry is characterized by C-N double and triple bonding environments distinct from what is usually found in 15N-enriched organics from aqueously altered carbonaceous chondrites. Our investigations demonstrate that Maribo represents one of the least altered CM chondrite breccias found to date and contains primordial organic matter, probably originating in the interstellar medium.
Collapse
Affiliation(s)
- Christian Vollmer
- Institut für Mineralogie, Westfälische Wilhelms-Universität, Corrensstr. 24, 48149, Münster, Germany.
| | - Jan Leitner
- Particle Chemistry Department, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128, Mainz, Germany
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, Keckwick Lane, Daresbury, WA4 4AD, UK.,Jeol Nanocentre and Department of Physics, University of York, Heslington, YO10 5DD, UK
| | - Quentin M Ramasse
- SuperSTEM Laboratory, Keckwick Lane, Daresbury, WA4 4AD, UK.,School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Ashley J King
- Planetary Materials Group, Department of Earth Sciences, Natural History Museum, London, SW7 5BD, UK
| | - Paul F Schofield
- Planetary Materials Group, Department of Earth Sciences, Natural History Museum, London, SW7 5BD, UK
| | - Addi Bischoff
- Institut für Planetologie, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Str. 10, 48149, Münster, Germany
| | | | - Peter Hoppe
- Particle Chemistry Department, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128, Mainz, Germany
| |
Collapse
|
20
|
Escobar Steinvall S, Ghisalberti L, Zamani RR, Tappy N, Hage FS, Stutz EZ, Zamani M, Paul R, Leran JB, Ramasse QM, Craig Carter W, Fontcuberta I Morral A. Heterotwin Zn 3P 2 superlattice nanowires: the role of indium insertion in the superlattice formation mechanism and their optical properties. Nanoscale 2020; 12:22534-22540. [PMID: 33090166 DOI: 10.1039/d0nr05852a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Zinc phosphide (Zn3P2) nanowires constitute prospective building blocks for next generation solar cells due to the combination of suitable optoelectronic properties and an abundance of the constituting elements in the Earth's crust. The generation of periodic superstructures along the nanowire axis could provide an additional mechanism to tune their functional properties. Here we present the vapour-liquid-solid growth of zinc phosphide superlattices driven by periodic heterotwins. This uncommon planar defect involves the exchange of Zn by In at the twinning boundary. We find that the zigzag superlattice formation is driven by reduction of the total surface energy of the liquid droplet. The chemical variation across the heterotwin does not affect the homogeneity of the optical properties, as measured by cathodoluminescence. The basic understanding provided here brings new propsects on the use of II-V semiconductors in nanowire technology.
Collapse
Affiliation(s)
- Simon Escobar Steinvall
- Laboratory of Semiconductor Materials, Institute of Materials École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Biskupek J, Skowron ST, Stoppiello CT, Rance GA, Alom S, Fung KLY, Whitby RJ, Levitt MH, Ramasse QM, Kaiser U, Besley E, Khlobystov AN. Bond Dissociation and Reactivity of HF and H 2O in a Nano Test Tube. ACS Nano 2020; 14:11178-11189. [PMID: 32816453 DOI: 10.1021/acsnano.0c02661] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Molecular motion and bond dissociation are two of the most fundamental phenomena underpinning the properties of molecular materials. We entrapped HF and H2O molecules within the fullerene C60 cage, encapsulated within a single-walled carbon nanotube (X@C60)@SWNT, where X = HF or H2O. (X@C60)@SWNT represents a class of molecular nanomaterial composed of a guest within a molecular host within a nanoscale host, enabling investigations of the interactions of isolated single di- or triatomic molecules with the electron beam. The use of the electron beam simultaneously as a stimulus of chemical reactions in molecules and as a sub-angstrom resolution imaging probe allows investigations of the molecular dynamics and reactivity in real time and at the atomic scale, which are probed directly by chromatic and spherical aberration-corrected high-resolution transmission electron microscopy imaging, or indirectly by vibrational electron energy loss spectroscopy in situ during scanning transmission electron microscopy experiments. Experimental measurements indicate that the electron beam triggers homolytic dissociation of the H-F or H-O bonds, respectively, causing the expulsion of the hydrogen atoms from the fullerene cage, leaving fluorine or oxygen behind. Because of a difference in the mechanisms of penetration through the carbon lattice available for F or O atoms, atomic fluorine inside the fullerene cage appears to be more stable than the atomic oxygen under the same conditions. The use of (X@C60)@SWNT, where each molecule X is "packaged" separately from each other, in combination with the electron microscopy methods and density functional theory modeling in this work, enable bond dynamics and reactivity of individual atoms to be probed directly at the single-molecule level.
Collapse
Affiliation(s)
- Johannes Biskupek
- Electron Microscopy of Materials Science, Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Stephen T Skowron
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Craig T Stoppiello
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Graham A Rance
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
- Nanoscale and Microscale Research Centre, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Shamim Alom
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Kayleigh L Y Fung
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Richard J Whitby
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Malcolm H Levitt
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury, WA4 4AD, United Kingdom
| | - Ute Kaiser
- Electron Microscopy of Materials Science, Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Elena Besley
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Andrei N Khlobystov
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| |
Collapse
|
22
|
Zamani M, Imbalzano G, Tappy N, Alexander DTL, Martí-Sánchez S, Ghisalberti L, Ramasse QM, Friedl M, Tütüncüoglu G, Francaviglia L, Bienvenue S, Hébert C, Arbiol J, Ceriotti M, Fontcuberta I Morral A. 3D Ordering at the Liquid-Solid Polar Interface of Nanowires. Adv Mater 2020; 32:e2001030. [PMID: 32762011 DOI: 10.1002/adma.202001030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/29/2020] [Indexed: 06/11/2023]
Abstract
The nature of the liquid-solid interface determines the characteristics of a variety of physical phenomena, including catalysis, electrochemistry, lubrication, and crystal growth. Most of the established models for crystal growth are based on macroscopic thermodynamics, neglecting the atomistic nature of the liquid-solid interface. Here, experimental observations and molecular dynamics simulations are employed to identify the 3D nature of an atomic-scale ordering of liquid Ga in contact with solid GaAs in a nanowire growth configuration. An interplay between the liquid ordering and the formation of a new bilayer is revealed, which, contrary to the established theories, suggests that the preference for a certain polarity and polytypism is influenced by the atomic structure of the interface. The conclusions of this work open new avenues for the understanding of crystal growth, as well as other processes and systems involving a liquid-solid interface.
Collapse
Affiliation(s)
- Mahdi Zamani
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Giulio Imbalzano
- Laboratory of Computational Science and Modeling, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Nicolas Tappy
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Duncan T L Alexander
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics, Faculty of Basic Sciences, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
- Interdisciplinary Centre for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, 08193, Spain
| | - Lea Ghisalberti
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury, WA4 4AD, UK
- School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Martin Friedl
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Gözde Tütüncüoglu
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Luca Francaviglia
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Sebastien Bienvenue
- Laboratory of Computational Science and Modeling, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Cécile Hébert
- Electron Spectrometry and Microscopy Laboratory, Institute of Physics, Faculty of Basic Sciences, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
- Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, 08193, Spain
- ICREA, Pg. Lluís Companys 23, Barcelona, Catalonia, 08010, Spain
| | - Michele Ceriotti
- Laboratory of Computational Science and Modeling, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| | - Anna Fontcuberta I Morral
- Laboratory of Semiconductor Materials, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
- Institute of Physics, Faculty of Basic Sciences, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland
| |
Collapse
|
23
|
Vorobyeva E, Gerken VC, Mitchell S, Sabadell-Rendón A, Hauert R, Xi S, Borgna A, Klose D, Collins SM, Midgley PA, Kepaptsoglou DM, Ramasse QM, Ruiz-Ferrando A, Fako E, Ortuño MA, López N, Carreira EM, Pérez-Ramírez J. Activation of Copper Species on Carbon Nitride for Enhanced Activity in the Arylation of Amines. ACS Catal 2020. [DOI: 10.1021/acscatal.0c03164] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Evgeniya Vorobyeva
- Department of Chemistry and Applied Biosciences, ETH Zürich,, Vladimir-Prelog-Weg 1-5, Zürich 8093, Switzerland
| | - Viktoria C. Gerken
- Department of Chemistry and Applied Biosciences, ETH Zürich,, Vladimir-Prelog-Weg 1-5, Zürich 8093, Switzerland
| | - Sharon Mitchell
- Department of Chemistry and Applied Biosciences, ETH Zürich,, Vladimir-Prelog-Weg 1-5, Zürich 8093, Switzerland
| | - Albert Sabadell-Rendón
- Institute of Chemical Research of Catalonia and The Barcelona Institute of Science and Technology, Tarragona 43007, Spain
| | - Roland Hauert
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf 8600, Switzerland
| | - Shibo Xi
- Institute of Chemical and Engineering Sciences, A*STAR, 1 Pesek Road, Jurong Island, Singapore 627833
| | - Armando Borgna
- Institute of Chemical and Engineering Sciences, A*STAR, 1 Pesek Road, Jurong Island, Singapore 627833
| | - Daniel Klose
- Department of Chemistry and Applied Biosciences, ETH Zürich,, Vladimir-Prelog-Weg 1-5, Zürich 8093, Switzerland
| | - Sean M. Collins
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, U.K
- School of Chemical and Process Engineering and School of Physics, University of Leeds, Leeds LS2 9JT, U.K
| | - Paul A. Midgley
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, U.K
| | - Demie M. Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- Department of Physics, University of York, York YO10 5DD, U.K
| | - Quentin M. Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- School of Chemical and Process Engineering and School of Physics, University of Leeds, Leeds LS2 9JT, U.K
| | - Andrea Ruiz-Ferrando
- Institute of Chemical Research of Catalonia and The Barcelona Institute of Science and Technology, Tarragona 43007, Spain
| | - Edvin Fako
- Institute of Chemical Research of Catalonia and The Barcelona Institute of Science and Technology, Tarragona 43007, Spain
| | - Manuel A. Ortuño
- Institute of Chemical Research of Catalonia and The Barcelona Institute of Science and Technology, Tarragona 43007, Spain
| | - Núria López
- Institute of Chemical Research of Catalonia and The Barcelona Institute of Science and Technology, Tarragona 43007, Spain
| | - Erick M. Carreira
- Department of Chemistry and Applied Biosciences, ETH Zürich,, Vladimir-Prelog-Weg 1-5, Zürich 8093, Switzerland
| | - Javier Pérez-Ramírez
- Department of Chemistry and Applied Biosciences, ETH Zürich,, Vladimir-Prelog-Weg 1-5, Zürich 8093, Switzerland
| |
Collapse
|
24
|
Asselin J, Boukouvala C, Hopper ER, Ramasse QM, Biggins JS, Ringe E. Tents, Chairs, Tacos, Kites, and Rods: Shapes and Plasmonic Properties of Singly Twinned Magnesium Nanoparticles. ACS Nano 2020; 14:5968-5980. [PMID: 32286792 PMCID: PMC7254836 DOI: 10.1021/acsnano.0c01427] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/14/2020] [Indexed: 05/26/2023]
Abstract
Nanostructures of some metals can sustain light-driven electron oscillations called localized surface plasmon resonances, or LSPRs, that give rise to absorption, scattering, and local electric field enhancement. Their resonant frequency is dictated by the nanoparticle (NP) shape and size, fueling much research geared toward discovery and control of new structures. LSPR properties also depend on composition; traditional, rare, and expensive noble metals (Ag, Au) are increasingly eclipsed by earth-abundant alternatives, with Mg being an exciting candidate capable of sustaining resonances across the ultraviolet, visible, and near-infrared spectral ranges. Here, we report numerical predictions and experimental verifications of a set of shapes based on Mg NPs displaying various twinning patterns including (101̅1), (101̅2), (101̅3), and (112̅1), that create tent-, chair-, taco-, and kite-shaped NPs, respectively. These are strikingly different from what is obtained for typical plasmonic metals because Mg crystallizes in a hexagonal close packed structure, as opposed to the cubic Al, Cu, Ag, and Au. A numerical survey of the optical response of the various structures, as well as the effect of size and aspect ratio, reveals their rich array of resonances, which are supported by single-particle optical scattering experiments. Further, corresponding numerical and experimental studies of the near-field plasmon distribution via scanning transmission electron microscopy electron-energy loss spectroscopy unravels a mode nature and distribution that are unlike those of either hexagonal plates or cylindrical rods. These NPs, made from earth-abundant Mg, provide interesting ways to control light at the nanoscale across the ultraviolet, visible, and near-infrared spectral ranges.
Collapse
Affiliation(s)
- Jérémie Asselin
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge, United Kingdom, CB3 0FS
- Department
of Earth Sciences, University of Cambridge, Downing Street, Cambridge, United Kingdom, CB2 3EQ
| | - Christina Boukouvala
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge, United Kingdom, CB3 0FS
- Department
of Earth Sciences, University of Cambridge, Downing Street, Cambridge, United Kingdom, CB2 3EQ
| | - Elizabeth R. Hopper
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge, United Kingdom, CB3 0FS
- Department
of Earth Sciences, University of Cambridge, Downing Street, Cambridge, United Kingdom, CB2 3EQ
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, United Kingdom, CB3 0AS
| | - Quentin M. Ramasse
- School
of Chemical and Process Engineering, University
of Leeds, 211 Clarendon
Road, Leeds, United Kingdom, LS2 9JT
- School
of Physics and Astronomy, University of
Leeds, Woodhouse, Leeds, United Kingdom, LS2 9JS
- SuperSTEM, SciTech Daresbury Science and Innovation Campus, Keckwick Lane, Warrington, United Kingdom, WA4 4AD
| | - John S. Biggins
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge, United Kingdom, CB2 1PZ
| | - Emilie Ringe
- Department
of Materials Science and Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge, United Kingdom, CB3 0FS
- Department
of Earth Sciences, University of Cambridge, Downing Street, Cambridge, United Kingdom, CB2 3EQ
| |
Collapse
|
25
|
Williams RE, Ramasse QM, McKenna KP, Phillips LJ, Yates PJ, Hutter OS, Durose K, Major JD, Mendis BG. Evidence for Self-healing Benign Grain Boundaries and a Highly Defective Sb 2Se 3-CdS Interfacial Layer in Sb 2Se 3 Thin-Film Photovoltaics. ACS Appl Mater Interfaces 2020; 12:21730-21738. [PMID: 32314567 DOI: 10.1021/acsami.0c03690] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The crystal structure of Sb2Se3 gives rise to unique properties that cannot otherwise be achieved with conventional thin-film photovoltaic materials, such as CdTe or Cu(In,Ga)Se2. It has previously been proposed that grain boundaries can be made benign provided only the weak van der Waals forces between the (Sb4Se6)n ribbons are disrupted. Here, it is shown that non-radiative recombination is suppressed even for grain boundaries cutting across the (Sb4Se6)n ribbons. This is due to a remarkable self-healing process, whereby atoms at the grain boundary can relax to remove any electronic defect states within the band gap. Grain boundaries can, however, impede charge transport due to the fact that carriers have a higher mobility along the (Sb4Se6)n ribbons. Because of the ribbon misorientation, certain grain boundaries can effectively block charge collection. Furthermore, it is shown that CdS is not a suitable emitter to partner Sb2Se3 due to Sb and Se interdiffusion. As a result, a highly defective Sb2Se3 interfacial layer is formed that potentially reduces device efficiency through interface recombination.
Collapse
Affiliation(s)
- Rhys E Williams
- Department of Physics, Durham University, South Road, Durham DH1 3LE, U.K
| | - Quentin M Ramasse
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, U.K
- SuperSTEM Laboratory, Daresbury Science and Innovation Campus, Daresbury WA4 4AD, U.K
| | - Keith P McKenna
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Laurie J Phillips
- Stephenson Institute for Renewable Energy, Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
| | - Peter J Yates
- Stephenson Institute for Renewable Energy, Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
| | - Oliver S Hutter
- Stephenson Institute for Renewable Energy, Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
- Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne NE1 8ST, U.K
| | - Ken Durose
- Stephenson Institute for Renewable Energy, Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
| | - Jonathan D Major
- Stephenson Institute for Renewable Energy, Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
| | - Budhika G Mendis
- Department of Physics, Durham University, South Road, Durham DH1 3LE, U.K
| |
Collapse
|
26
|
McGilvery CM, Abellan P, Kłosowski MM, Livingston AG, Cabral JT, Ramasse QM, Porter AE. Nanoscale Chemical Heterogeneity in Aromatic Polyamide Membranes for Reverse Osmosis Applications. ACS Appl Mater Interfaces 2020; 12:19890-19902. [PMID: 32255610 DOI: 10.1021/acsami.0c01473] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Reverse osmosis membranes are used within the oil and gas industry for seawater desalination on off-shore oilrigs. The membranes consist of three layers of material: a polyester backing layer, a polysulfone support and a polyamide (PA) thin film separating layer. It is generally thought that the PA layer controls ion selectivity within the membrane but little is understood about its structure or chemistry at the molecular scale. This active polyamide layer is synthesized by interfacial polymerization at an organic/aqueous interface between m-phenylenediamine and trimesoyl chloride, producing a highly cross-linked PA polymer. It has been speculated that the distribution of functional chemistry within this layer could play a role in solute filtration. The only technique potentially capable of probing the distribution of functional chemistry within the active PA layer with sufficient spatial and energy resolution is scanning transmission electron microscopy combined with electron energy-loss spectroscopy (STEM-EELS). Its use is a challenge because organic materials suffer beam-induced damage at relatively modest electron doses. Here we show that it is possible to use the N K-edge to map the active layer of a PA film using monochromated EELS spectrum imaging. The active PA layer is 12 nm thick, which supports previous neutron reflectivity data. Clear changes in the fine structure of the C K-edge across the PA films are measured and we use machine learning to assign fine structure at this edge. Using this method, we map highly heterogeneous intensity variations in functional chemistry attributed to N-C═C bonds within the PA. Similarities are found with previous molecular dynamics simulations of PA showing regions with a higher density of amide bonding as a result of the aggregation process at similar length scales. The chemical pathways that can be deduced may offer a clearer understanding of the transport mechanisms through the membrane.
Collapse
Affiliation(s)
- Catriona M McGilvery
- Department of Materials and London Centre for Nanotechnology, Imperial College, London SW7 2AZ, United Kingdom
| | - Patricia Abellan
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, WA4 4AD, United Kingdom
| | - Michał M Kłosowski
- Department of Materials and London Centre for Nanotechnology, Imperial College, London SW7 2AZ, United Kingdom
| | - Andrew G Livingston
- Department of Chemical Engineering, Imperial College, London SW7 2AZ, United Kingdom
| | - João T Cabral
- Department of Chemical Engineering, Imperial College, London SW7 2AZ, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, WA4 4AD, United Kingdom
- School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Alexandra E Porter
- Department of Materials and London Centre for Nanotechnology, Imperial College, London SW7 2AZ, United Kingdom
| |
Collapse
|
27
|
Hage FS, Radtke G, Kepaptsoglou DM, Lazzeri M, Ramasse QM. Single-atom vibrational spectroscopy in the scanning transmission electron microscope. Science 2020; 367:1124-1127. [PMID: 32139541 DOI: 10.1126/science.aba1136] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 02/03/2020] [Indexed: 11/02/2022]
Abstract
Single-atom impurities and other atomic-scale defects can notably alter the local vibrational responses of solids and, ultimately, their macroscopic properties. Using high-resolution electron energy-loss spectroscopy in the electron microscope, we show that a single substitutional silicon impurity in graphene induces a characteristic, localized modification of the vibrational response. Extensive ab initio calculations reveal that the measured spectroscopic signature arises from defect-induced pseudo-localized phonon modes-that is, resonant states resulting from the hybridization of the defect modes and the bulk continuum-with energies that can be directly matched to the experiments. This finding realizes the promise of vibrational spectroscopy in the electron microscope with single-atom sensitivity and has broad implications across the fields of physics, chemistry, and materials science.
Collapse
Affiliation(s)
- F S Hage
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, UK
| | - G Radtke
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, 75005 Paris, France.
| | - D M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, UK.,York Nanocentre and Department of Physics, University of York, Heslington, York YO10 5DD, UK
| | - M Lazzeri
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, 75005 Paris, France
| | - Q M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, UK. .,School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| |
Collapse
|
28
|
Collins SM, Kepaptsoglou DM, Hou J, Ashling CW, Radtke G, Bennett TD, Midgley PA, Ramasse QM. Functional Group Mapping by Electron Beam Vibrational Spectroscopy from Nanoscale Volumes. Nano Lett 2020; 20:1272-1279. [PMID: 31944111 DOI: 10.1021/acs.nanolett.9b04732] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Vibrational spectroscopies directly record details of bonding in materials, but spatially resolved methods have been limited to surface techniques for mapping functional groups at the nanoscale. Electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope presents a route to functional group analysis from nanoscale volumes using transmitted subnanometer electron probes. Here, we now use vibrational EELS to map distinct carboxylate and imidazolate linkers in a metal-organic framework (MOF) crystal-glass composite material. Domains <100 nm in size are observed using vibrational EELS, with recorded spatial resolution <15 nm at interfaces in the composite. This nanoscale functional group mapping is confirmed by correlated EELS at core ionization edges as well as X-ray energy dispersive spectroscopy for elemental mapping of the metal centers of the two constituent MOFs. These results present a complete nanoscale analysis of the building blocks of the MOF composite and establish spatially resolved functional group analysis using electron beam spectroscopy for crystalline and amorphous organic and metal-organic solids.
Collapse
Affiliation(s)
- Sean M Collins
- Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom
| | - Demie M Kepaptsoglou
- SuperSTEM Laboratory , SciTech Daresbury Campus , Daresbury WA4 4AD , United Kingdom
- Department of Physics , University of York , Heslington, York YO10 5DD , United Kingdom
| | - Jingwei Hou
- Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom
| | - Christopher W Ashling
- Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom
| | - Guillaume Radtke
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC , 75005 Paris , France
| | - Thomas D Bennett
- Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom
| | - Paul A Midgley
- Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory , SciTech Daresbury Campus , Daresbury WA4 4AD , United Kingdom
- School of Chemical and Process Engineering and School of Physics , University of Leeds , Leeds LS2 9JT , United Kingdom
| |
Collapse
|
29
|
Raya AM, Friedl M, Martí-Sánchez S, Dubrovskii VG, Francaviglia L, Alén B, Morgan N, Tütüncüoglu G, Ramasse QM, Fuster D, Llorens JM, Arbiol J, Fontcuberta I Morral A. GaAs nanoscale membranes: prospects for seamless integration of III-Vs on silicon. Nanoscale 2020; 12:815-824. [PMID: 31830194 DOI: 10.1039/c9nr08453c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The growth of compound semiconductors on silicon has been widely sought after for decades, but reliable methods for defect-free combination of these materials have remained elusive. Recently, interconnected GaAs nanoscale membranes have been used as templates for the scalable integration of nanowire networks on III-V substrates. Here, we demonstrate how GaAs nanoscale membranes can be seamlessly integrated on silicon by controlling the density of nuclei in the initial stages of growth. We also correlate the absence or presence of defects with the existence of a single or multiple nucleation regime for the single membranes. Certain defects exhibit well-differentiated spectroscopic features that we identify with cathodoluminescence and micro-photoluminescence techniques. Overall, this work presents a new approach for the seamless integration of compound semiconductors on silicon.
Collapse
Affiliation(s)
- Andrés M Raya
- Laboratoire des Matériaux Semiconducteurs, Institute of Materials, Faculty of Engineering, École Polytechnique Fédérale de Lausanne, EPFL, 1015 Lausanne, Switzerland.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
He Y, Tang P, Hu Z, He Q, Zhu C, Wang L, Zeng Q, Golani P, Gao G, Fu W, Huang Z, Gao C, Xia J, Wang X, Wang X, Zhu C, Ramasse QM, Zhang A, An B, Zhang Y, Martí-Sánchez S, Morante JR, Wang L, Tay BK, Yakobson BI, Trampert A, Zhang H, Wu M, Wang QJ, Arbiol J, Liu Z. Engineering grain boundaries at the 2D limit for the hydrogen evolution reaction. Nat Commun 2020; 11:57. [PMID: 31896753 PMCID: PMC6940382 DOI: 10.1038/s41467-019-13631-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 11/01/2019] [Indexed: 11/17/2022] Open
Abstract
Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis. So far, their edges, dopant heteroatoms and defects have been intensively explored as active sites for the hydrogen evolution reaction (HER) to split water. However, grain boundaries (GBs), a key type of defects in TMDs, have been overlooked due to their low density and large structural variations. Here, we demonstrate the synthesis of wafer-size atom-thin TMD films with an ultra-high-density of GBs, up to ~1012 cm-2. We propose a climb and drive 0D/2D interaction to explain the underlying growth mechanism. The electrocatalytic activity of the nanograin film is comprehensively examined by micro-electrochemical measurements, showing an excellent hydrogen-evolution performance (onset potential: -25 mV and Tafel slope: 54 mV dec-1), thus indicating an intrinsically high activation of the TMD GBs.
Collapse
Affiliation(s)
- Yongmin He
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Center for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, Singapore, 639798, Singapore
| | - Pengyi Tang
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Catalonia, Spain
- Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, 08930, Catalonia, Spain
| | - Zhili Hu
- College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Qiyuan He
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Luqing Wang
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Qingsheng Zeng
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Prafful Golani
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Guanhui Gao
- Paul-Drude-Institut für Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin Hausvogteiplatz, 5-7, 10117, Berlin, Germany
| | - Wei Fu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Zhiqi Huang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Caitian Gao
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Juan Xia
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Xingli Wang
- CNRS-International-NTU-THALES Research Alliance, Nanyang Technological University, Singaproe, 637553, Singapore
| | - Xuewen Wang
- Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Chao Zhu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury, WA44AD, UK
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS29JT, UK
| | - Ao Zhang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Boxing An
- College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
| | - Yongzhe Zhang
- College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Catalonia, Spain
| | - Joan Ramon Morante
- Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, 08930, Catalonia, Spain
| | - Liang Wang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Beng Kang Tay
- CNRS-International-NTU-THALES Research Alliance, Nanyang Technological University, Singaproe, 637553, Singapore
| | - Boris I Yakobson
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Achim Trampert
- Paul-Drude-Institut für Festkörperelektronik Leibniz-Institut im Forschungsverbund Berlin Hausvogteiplatz, 5-7, 10117, Berlin, Germany
| | - Hua Zhang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Minghong Wu
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
| | - Qi Jie Wang
- Center for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, Singapore, 639798, Singapore.
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore.
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Catalonia, Spain.
- ICREA, Pg. Lluís Companys 23, Barcelona, 08010, Catalonia, Spain.
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
- Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, Singapore, 637553, Singapore.
- Environmental Chemistry and Materials Centre, Nanyang Environment and Water Research Institute, Singapore, Singapore.
| |
Collapse
|
31
|
Azough F, Gholinia A, Alvarez-Ruiz DT, Duran E, Kepaptsoglou DM, Eggeman AS, Ramasse QM, Freer R. Self-Nanostructuring in SrTiO 3: A Novel Strategy for Enhancement of Thermoelectric Response in Oxides. ACS Appl Mater Interfaces 2019; 11:32833-32843. [PMID: 31419381 DOI: 10.1021/acsami.9b06483] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanostructuring is recognized as an efficient route for enhancing thermoelectric response. Here, we report a new synthesis strategy for nanostructuring oxide ceramics and demonstrate its effectiveness on an important n-type thermoelectric SrTiO3. Ceramics of Sr0.9La0.1TiO3 with additions of B2O3 were synthesized by the mixed oxide route. Samples were sintered in air followed by annealing in a reducing atmosphere. Crystallographic data from X-ray and electron diffraction showed Pm3̅m cubic symmetry for all the samples. High-resolution transmission electron microscopy (HRTEM) showed the formation of a core-shell type structure within the grains for the annealed ceramics. The cores contain nanosize features comprising pairs of nanosize voids and particles; the feature sizes depend on annealing time. Atomic-resolution, high-angle annular-dark-field imaging and electron energy loss spectroscopy in the scanning transmission electron microscopy (STEM-HAADF-EELS) showed the particles to be rich in Ti and the areas around the voids to contain high concentrations of Ti3+. Additionally, dislocations were observed, with significantly higher densities in the shell areas. The observed dislocations are combined (100) and (110) edge dislocations. The major impact of the core-shell type microstructures, with nanosize inclusions, is the reduction of the thermal conductivity. Sr0.9La0.1TiO3 ceramics containing grain boundary shells of size ≈ 1 μm and inclusions in the core of 60-80 nm exhibit a peak power factor of 1600 μW/m·K2 at 540 K; at 1000 K, they exhibit a low thermal conductivity (2.75 W/m·K) and a power factor of 1050 μW/m·K2 leading to a high of ZT of 0.39 ± 0.03. This is the highest ZT reported so far for Sr0.9La0.1TiO3 based-compositions. This nanostructuring strategy should be readily applicable to other functional oxides.
Collapse
Affiliation(s)
- Feridoon Azough
- School of Materials , University of Manchester , Manchester , M13 9PL , U.K
| | - Ali Gholinia
- School of Materials , University of Manchester , Manchester , M13 9PL , U.K
| | | | - Ercin Duran
- School of Materials , University of Manchester , Manchester , M13 9PL , U.K
| | - Demie M Kepaptsoglou
- SuperSTEM Laboratory , STFC Daresbury Campus , Daresbury WA4 4AD , U.K
- Jeol Nanocentre and Department of Physics , University of York , Heslington, York YO10 5DD , U.K
| | | | - Quentin M Ramasse
- SuperSTEM Laboratory , STFC Daresbury Campus , Daresbury WA4 4AD , U.K
- School of Chemical and Process Engineering and School of Physics , University of Leeds , Leeds LS2 9JT , U.K
| | - Robert Freer
- School of Materials , University of Manchester , Manchester , M13 9PL , U.K
| |
Collapse
|
32
|
Abstract
Advances in source monochromation in transmission electron microscopy have opened up new possibilities for investigations of condensed matter using the phonon-loss sector of the energy-loss spectrum. Here, we explore the spatial variations of the spectrum as an atomic-sized probe is scanned across a thin flake of hexagonal boron nitride. We demonstrate that phonon spectral mapping of atomic structure is possible. These results are consistent with a model for the quantum excitation of phonons and confirm that Z-contrast imaging is based on inelastic scattering associated with phonon excitation.
Collapse
Affiliation(s)
- F S Hage
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
| | - D M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- York JEOL Nanocentre and Department of Physics, University of York, Heslington, York YO10 5BR, United Kingdom
| | - Q M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- School of Physics and School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - L J Allen
- School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425 Jülich, Germany
| |
Collapse
|
33
|
Collins SM, Kepaptsoglou DM, Butler KT, Longley L, Bennett TD, Ramasse QM, Midgley PA. Subwavelength Spatially Resolved Coordination Chemistry of Metal–Organic Framework Glass Blends. J Am Chem Soc 2018; 140:17862-17866. [DOI: 10.1021/jacs.8b11548] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Sean M. Collins
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Demie M. Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Keith T. Butler
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - Louis Longley
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Thomas D. Bennett
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Quentin M. Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- School of Chemical and Process Engineering and School of Physics, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Paul A. Midgley
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| |
Collapse
|
34
|
Sheehan M, Ramasse QM, Geaney H, Ryan KM. Linear heterostructured Ni 2Si/Si nanowires with abrupt interfaces synthesised in solution. Nanoscale 2018; 10:19182-19187. [PMID: 30302485 DOI: 10.1039/c8nr05388j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Herein, we report a novel approach to form axial heterostructure nanowires composed of linearly distinct Ni silicide (Ni2Si) and Si segments via a one-pot solution synthesis method. Initially, Si nanowires are grown using Au seeds deposited on a Ni substrate with the Si delivery in the solution phase using a liquid phenylsilane precursor. Ni silicide then forms axially along the wires through progressive Ni diffusion from the growth substrate, with a distinct transition between the silicide and pure Si segments. The interfacial abruptness and chemical composition of the heterostructure nanowires was analysed through transmission electron microscopy, electron diffraction, energy dispersive X-ray spectroscopy, aberration corrected scanning transmission electron microscopy and atomically resolved electron energy loss spectroscopy. The method represents a versatile approach for the formation of complex axial NW heterostructures and could be extended to other metal silicide or analogous metal germanide systems.
Collapse
Affiliation(s)
- Martin Sheehan
- Department of Chemical Sciences and Bernal Institute, University of limerick, V94 T9PX, Ireland.
| | | | | | | |
Collapse
|
35
|
Trump BA, Koohpayeh SM, Livi KJT, Wen JJ, Arpino KE, Ramasse QM, Brydson R, Feygenson M, Takeda H, Takigawa M, Kimura K, Nakatsuji S, Broholm CL, McQueen TM. Universal geometric frustration in pyrochlores. Nat Commun 2018; 9:2619. [PMID: 29976983 PMCID: PMC6033937 DOI: 10.1038/s41467-018-05033-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 06/05/2018] [Indexed: 11/28/2022] Open
Abstract
Materials with the pyrochlore/fluorite structure have diverse technological applications, from magnetism to nuclear waste disposal. Here we report the observation of structural instability present in the pyrochlores A2Zr2O6Oʹ (A = Pr, La) and Yb2Ti2O6Oʹ, that exists despite ideal stoichiometry, ideal cation-ordering, the absence of lone pair effects, and a lack of magnetic order. Though these materials appear to have good long-range order, local structure probes find displacements, of the order of 0.01 nm, within the pyrochlore framework. The pattern of displacements of the A2Oʹ sublattice mimics the entropically-driven fluxional motions characteristic of and well-known in the silica mineral β-cristobalite. The universality of such displacements within the pyrochlore structure adds to the known structural diversity and explains the extreme sensitivity to composition found in quantum spin ices and the lack of ferroelectric behavior in pyrochlores. The family of pyrochlore complex oxides includes many materials of fundamental or practical interest, such as spin ices and dielectrics. Trump et al. show that flexibility of the pyrochlores’ structure leads to local displacements that explain some of their unusual physical properties.
Collapse
Affiliation(s)
- B A Trump
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.,Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - S M Koohpayeh
- Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - K J T Livi
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - J-J Wen
- Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - K E Arpino
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Q M Ramasse
- SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury, WA4 4AD, UK
| | - R Brydson
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - M Feygenson
- Jülich Center for Neutron Science, Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
| | - H Takeda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - M Takigawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - K Kimura
- Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - S Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - C L Broholm
- Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - T M McQueen
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA. .,Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA. .,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.
| |
Collapse
|
36
|
Vasylenko A, Marks S, Wynn JM, Medeiros PVC, Ramasse QM, Morris AJ, Sloan J, Quigley D. Electronic Structure Control of Sub-nanometer 1D SnTe via Nanostructuring within Single-Walled Carbon Nanotubes. ACS Nano 2018; 12:6023-6031. [PMID: 29782147 DOI: 10.1021/acsnano.8b02261] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nanostructuring, e. g., reduction of dimensionality in materials, offers a viable route toward regulation of materials electronic and hence functional properties. Here, we present the extreme case of nanostructuring, exploiting the capillarity of single-walled carbon nanotubes (SWCNTs) for the synthesis of the smallest possible SnTe nanowires with cross sections as thin as a single atom column. We demonstrate that by choosing the appropriate diameter of a template SWCNT, we can manipulate the structure of the quasi-one-dimensional (1D) SnTe to design electronic behavior. From first principles, we predict the structural re-formations that SnTe undergoes in varying encapsulations and confront the prediction with TEM imagery. To further illustrate the control of physical properties by nanostructuring, we study the evolution of transport properties in a homologous series of models of synthesized and isolated SnTe nanowires varying only in morphology and atomic layer thickness. This extreme scaling is predicted to significantly enhance thermoelectric performance of SnTe, offering a prospect for further experimental studies and future applications.
Collapse
Affiliation(s)
- Andrij Vasylenko
- Department of Physics , University of Warwick , Coventry , CV4 7AL , United Kingdom
| | - Samuel Marks
- Department of Physics , University of Warwick , Coventry , CV4 7AL , United Kingdom
| | - Jamie M Wynn
- Cavendish Laboratory , University of Cambridge , Cambridge , CB3 0HE , United Kingdom
| | - Paulo V C Medeiros
- Cavendish Laboratory , University of Cambridge , Cambridge , CB3 0HE , United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus , Daresbury , WA44AD , United Kingdom
| | - Andrew J Morris
- School of Metallurgy and Materials , University of Birmingham , Birmingham , B15 2TT , United Kingdom
| | - Jeremy Sloan
- Department of Physics , University of Warwick , Coventry , CV4 7AL , United Kingdom
| | - David Quigley
- Department of Physics , University of Warwick , Coventry , CV4 7AL , United Kingdom
| |
Collapse
|
37
|
Hage FS, Nicholls RJ, Yates JR, McCulloch DG, Lovejoy TC, Dellby N, Krivanek OL, Refson K, Ramasse QM. Nanoscale momentum-resolved vibrational spectroscopy. Sci Adv 2018; 4:eaar7495. [PMID: 29951584 PMCID: PMC6018998 DOI: 10.1126/sciadv.aar7495] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 05/01/2018] [Indexed: 05/21/2023]
Abstract
Vibrational modes affect fundamental physical properties such as the conduction of sound and heat and can be sensitive to nano- and atomic-scale structure. Probing the momentum transfer dependence of vibrational modes provides a wealth of information about a materials system; however, experimental work has been limited to essentially bulk and averaged surface approaches or to small wave vectors. We demonstrate a combined experimental and theoretical methodology for nanoscale mapping of optical and acoustic phonons across the first Brillouin zone, in the electron microscope, probing a volume ~1010 to 1020 times smaller than that of comparable bulk and surface techniques. In combination with more conventional electron microscopy techniques, the presented methodology should allow for direct correlation of nanoscale vibrational mode dispersions with atomic-scale structure and chemistry.
Collapse
Affiliation(s)
- Fredrik S. Hage
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK
- Corresponding author. (Q.M.R.); (F.S.H.)
| | - Rebecca J. Nicholls
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Jonathan R. Yates
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Dougal G. McCulloch
- Physics, School of Science, RMIT University, Melbourne, Victoria 3001, Australia
| | | | - Niklas Dellby
- Nion Company, 11511 NE 118th Street, Kirkland, WA 98034, USA
| | - Ondrej L. Krivanek
- Nion Company, 11511 NE 118th Street, Kirkland, WA 98034, USA
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - Keith Refson
- STFC (Science & Technology Facilities Council) Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, UK
- Department of Physics, Royal Holloway, University of London, Egham TW20 0EX, UK
| | - Quentin M. Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK
- School of Physics, University of Leeds, Leeds LS2 9JT, UK
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK
- Corresponding author. (Q.M.R.); (F.S.H.)
| |
Collapse
|
38
|
Abellan P, El-Khoury PZ, Ramasse QM. Mapping VIS-terahertz (≤17 THz) surface plasmons sustained on native and chemically functionalized percolated gold thin films using EELS. Microscopy (Oxf) 2018; 67:i30-i39. [PMID: 29136197 DOI: 10.1093/jmicro/dfx092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/08/2017] [Indexed: 01/25/2023] Open
Abstract
Heterogeneous assemblies of molecules (Rhodamine B) adsorbed onto a nano-corrugated metallic surface (a percolated Au network) are investigated using electron energy loss spectroscopy in the scanning transmission electron microscope (STEM-EELS). Our first measurements target the native metallic substrate, which consists of a commercial Au thin film atop an ultrathin carbon membrane. The Au film displays a percolated morphology with nanostructures of estimated thickness ≤10 nm approximately. We observe a rich plasmonic response from the metallic substrate; one which varies nanometrically and spans the VIS-terahertz region. Multiple localized plasmons are detected at individual nanometric integrated areas, while an analysis of their spatial distribution reveals that for each integrated energy range (50 meV integration window) resonances are simultaneously supported at different locations within the film. We record subsequent EEL spectrum images of the hybrid molecular-metallic construct after deposition of Rhodamine B molecules onto the substrate, where plasmons, molecular vibrations and electronic excitations might all be simultaneously detected. A comparison of average signals for both systems is performed and spectral variations within the three spectral regions where molecular signatures may be observed are discussed. Our measurements and their analysis, if applied to the same location before and after molecular deposition, may be used to rationalize optical microscopic and spectroscopic measurements that take advantage of the interplay between molecules and plasmons.
Collapse
Affiliation(s)
- Patricia Abellan
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK
| | - Patrick Z El-Khoury
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK
| |
Collapse
|
39
|
Jones L, Varambhia A, Beanland R, Kepaptsoglou D, Griffiths I, Ishizuka A, Azough F, Freer R, Ishizuka K, Cherns D, Ramasse QM, Lozano-Perez S, Nellist PD. Managing dose-, damage- and data-rates in multi-frame spectrum-imaging. Microscopy (Oxf) 2018; 67:i98-i113. [PMID: 29340597 DOI: 10.1093/jmicro/dfx125] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 12/05/2017] [Indexed: 11/12/2022] Open
Abstract
As an instrument, the scanning transmission electron microscope is unique in being able to simultaneously explore both local structural and chemical variations in materials at the atomic scale. This is made possible as both types of data are acquired serially, originating simultaneously from sample interactions with a sharply focused electron probe. Unfortunately, such scanned data can be distorted by environmental factors, though recently fast-scanned multi-frame imaging approaches have been shown to mitigate these effects. Here, we demonstrate the same approach but optimized for spectroscopic data; we offer some perspectives on the new potential of multi-frame spectrum-imaging (MFSI) and show how dose-sharing approaches can reduce sample damage, improve crystallographic fidelity, increase data signal-to-noise, or maximize usable field of view. Further, we discuss the potential issue of excessive data-rates in MFSI, and demonstrate a file-compression approach to significantly reduce data storage and transmission burdens.
Collapse
Affiliation(s)
- Lewys Jones
- School of Physics, Trinity College Dublin, Dublin 2, Ireland.,Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures and Nanodevices, Dublin 2, Ireland.,Department of Materials, University of Oxford, Oxford, UK
| | | | | | | | - Ian Griffiths
- Department of Materials, University of Oxford, Oxford, UK.,University of Bristol, Bristol, UK
| | | | - Feridoon Azough
- School of Materials, University of Manchester, Manchester, UK
| | - Robert Freer
- School of Materials, University of Manchester, Manchester, UK
| | | | | | | | | | | |
Collapse
|
40
|
Abstract
Over the past decade, III-V heterostructure nanowires have attracted a surge of attention for their application in novel semiconductor devices such as tunneling field-effect transistors (TFETs). The functionality of such devices critically depends on the specific atomic arrangement at the semiconductor heterointerfaces. However, most of the currently available characterization techniques lack sufficient spatial resolution to provide local information on the atomic structure and composition of these interfaces. Atomic-resolution spectrum imaging by means of electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) is a powerful technique with the potential to resolve structure and chemical composition with sub-angstrom spatial resolution and to provide localized information about the physical properties of the material at the atomic scale. Here, we demonstrate the use of atomic-resolution EELS to understand the interface atomic arrangement in three-dimensional heterostructures in semiconductor nanowires. We observed that the radial interfaces of GaSb-InAs heterostructure nanowires are atomically abrupt, while the axial interface in contrast consists of an interfacial region where intermixing of the two compounds occurs over an extended spatial region. The local atomic configuration affects the band alignment at the interface and, hence, the charge transport properties of devices such as GaSb-InAs nanowire TFETs. STEM-EELS thus represents a very promising technique for understanding nanowire physical properties, such as differing electrical behavior across the radial and axial heterointerfaces of GaSb-InAs nanowires for TFET applications.
Collapse
Affiliation(s)
- Reza R Zamani
- Solid-State Physics , Lund University , Box 118, Lund 22100 , Sweden
| | - Fredrik S Hage
- SuperSTEM Laboratory, SciTech Daresbury Campus , Keckwick Lane , Warrington WA4 4AD , United Kingdom
| | - Sebastian Lehmann
- Solid-State Physics , Lund University , Box 118, Lund 22100 , Sweden
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus , Keckwick Lane , Warrington WA4 4AD , United Kingdom
| | - Kimberly A Dick
- Solid-State Physics , Lund University , Box 118, Lund 22100 , Sweden
- Centre for Analysis and Synthesis , Lund University , Box 124, Lund 22100 , Sweden
| |
Collapse
|
41
|
Ramasse QM, van Aken PA, Kurata H. EDGE 2017 - Enhanced Data Generated by Electrons, Okinawa, May 2017. Microscopy (Oxf) 2018; 67:i1-i2. [PMID: 29584930 DOI: 10.1093/jmicro/dfy013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Indexed: 11/14/2022] Open
Affiliation(s)
- Q M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, UK.,School of Chemical and Process Engineering, School of Physics, University of Leeds, Leeds, LS2 9JT, UK
| | - P A van Aken
- Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - H Kurata
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| |
Collapse
|
42
|
Hage FS, Hardcastle TP, Gjerding MN, Kepaptsoglou DM, Seabourne CR, Winther KT, Zan R, Amani JA, Hofsaess HC, Bangert U, Thygesen KS, Ramasse QM. Local Plasmon Engineering in Doped Graphene. ACS Nano 2018; 12:1837-1848. [PMID: 29369611 DOI: 10.1021/acsnano.7b08650] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Single-atom B or N substitutional doping in single-layer suspended graphene, realized by low-energy ion implantation, is shown to induce a dampening or enhancement of the characteristic interband π plasmon of graphene through a high-resolution electron energy loss spectroscopy study using scanning transmission electron microscopy. A relative 16% decrease or 20% increase in the π plasmon quality factor is attributed to the presence of a single substitutional B or N atom dopant, respectively. This modification is in both cases shown to be relatively localized, with data suggesting the plasmonic response tailoring can no longer be detected within experimental uncertainties beyond a distance of approximately 1 nm from the dopant. Ab initio calculations confirm the trends observed experimentally. Our results directly confirm the possibility of tailoring the plasmonic properties of graphene in the ultraviolet waveband at the atomic scale, a crucial step in the quest for utilizing graphene's properties toward the development of plasmonic and optoelectronic devices operating at ultraviolet frequencies.
Collapse
Affiliation(s)
| | - Trevor P Hardcastle
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- School of Chemical and Process Engineering, University of Leeds , Leeds LS2 9JT, U.K
| | - Morten N Gjerding
- CAMD and Center for Nanostructured Graphene (CNG), Technical University of Denmark , Fysikvej 1, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Demie M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- York NanoCentre, University of York , Heslington, York YO10 5BR, U.K
| | - Che R Seabourne
- School of Chemical and Process Engineering, University of Leeds , Leeds LS2 9JT, U.K
| | - Kirsten T Winther
- CAMD and Center for Nanostructured Graphene (CNG), Technical University of Denmark , Fysikvej 1, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Recep Zan
- Nanotechnology Application and Research Center, Niğde Omer Halisdemir University , Niğde 51000, Turkey
| | - Julian Alexander Amani
- II Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hans C Hofsaess
- II Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Ursel Bangert
- Bernal Institute and Department of Physics, University of Limerick , Limerick, Ireland
| | - Kristian S Thygesen
- CAMD and Center for Nanostructured Graphene (CNG), Technical University of Denmark , Fysikvej 1, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- School of Chemical and Process Engineering, University of Leeds , Leeds LS2 9JT, U.K
- School of Physics, University of Leeds , Leeds LS2 9JT, U.K
| |
Collapse
|
43
|
Glover SE, Saerbeck T, Achinuq B, Ghasemi A, Kepaptsoglou D, Ramasse QM, Yamada S, Hamaya K, Hase TPA, Lazarov VK, Bell GR. Magnetic and structural depth profiles of Heusler alloy Co 2FeAl 0.5Si 0.5 epitaxial films on Si(1 1 1). J Phys Condens Matter 2018; 30:065801. [PMID: 29337694 DOI: 10.1088/1361-648x/aaa4c8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The depth-resolved chemical structure and magnetic moment of [Formula: see text], thin films grown on Si(1 1 1) have been determined using x-ray and polarized neutron reflectometry. Bulk-like magnetization is retained across the majority of the film, but reduced moments are observed within 45[Formula: see text] of the surface and in a 25[Formula: see text] substrate-interface region. The reduced moment is related to compositional changes due to oxidation and diffusion, which are further quantified by elemental profiling using electron microscopy with electron energy loss spectroscopy. The accuracy of structural and magnetic depth-profiles obtained from simultaneous modeling is discussed using different approaches with different degree of constraints on the parameters. Our approach illustrates the challenges in fitting reflectometry data from these multi-component quaternary Heusler alloy thin films.
Collapse
Affiliation(s)
- Stephanie E Glover
- Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | | | - Barat Achinuq
- Department of Physics, University of York, York, YO10 5DD, United Kingdom
| | - Arsham Ghasemi
- Department of Physics, University of York, York, YO10 5DD, United Kingdom
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, WA4 4AD, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, WA4 4AD, United Kingdom
| | - Shinya Yamada
- Department of Systems Innovation, Osaka University, Osaka 560-8531, Japan
| | - Kohei Hamaya
- Department of Systems Innovation, Osaka University, Osaka 560-8531, Japan
| | - Thomas P A Hase
- Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Vlado K Lazarov
- Department of Physics, University of York, York, YO10 5DD, United Kingdom
| | - Gavin R Bell
- Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom
| |
Collapse
|
44
|
Denny MS, Parent LR, Patterson JP, Meena SK, Pham H, Abellan P, Ramasse QM, Paesani F, Gianneschi NC, Cohen SM. Transmission Electron Microscopy Reveals Deposition of Metal Oxide Coatings onto Metal–Organic Frameworks. J Am Chem Soc 2018; 140:1348-1357. [DOI: 10.1021/jacs.7b10453] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Michael S. Denny
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Lucas R. Parent
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Joseph P. Patterson
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
- Laboratory
of Materials and Interface Chemistry and Center of Multiscale Electron
Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
| | - Santosh Kumar Meena
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Huy Pham
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Patricia Abellan
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
| | - Quentin M. Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
| | - Francesco Paesani
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Nathan C. Gianneschi
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Seth M. Cohen
- Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| |
Collapse
|
45
|
Kepaptsoglou D, Baran JD, Azough F, Ekren D, Srivastava D, Molinari M, Parker SC, Ramasse QM, Freer R. Prospects for Engineering Thermoelectric Properties in La 1/3NbO 3 Ceramics Revealed via Atomic-Level Characterization and Modeling. Inorg Chem 2017; 57:45-55. [PMID: 29257680 DOI: 10.1021/acs.inorgchem.7b01584] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A combination of experimental and computational techniques has been employed to explore the crystal structure and thermoelectric properties of A-site-deficient perovskite La1/3NbO3 ceramics. Crystallographic data from X-ray and electron diffraction confirmed that the room temperature structure is orthorhombic with Cmmm as a space group. Atomically resolved imaging and analysis showed that there are two distinct A sites: one is occupied with La and vacancies, and the second site is fully unoccupied. The diffuse superstructure reflections observed through diffraction techniques are shown to originate from La vacancy ordering. La1/3NbO3 ceramics sintered in air showed promising high-temperature thermoelectric properties with a high Seebeck coefficient of S1 = -650 to -700 μV/K and a low and temperature-stable thermal conductivity of k = 2-2.2 W/m·K in the temperature range of 300-1000 K. First-principles electronic structure calculations are used to link the temperature dependence of the Seebeck coefficient measured experimentally to the evolution of the density of states with temperature and indicate possible avenues for further optimization through electron doping and control of the A-site occupancies. Moreover, lattice thermal conductivity calculations give insights into the dependence of the thermal conductivity on specific crystallographic directions of the material, which could be exploited via nanostructuring to create high-efficiency compound thermoelectrics.
Collapse
Affiliation(s)
| | - Jakub D Baran
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | - Feridoon Azough
- School of Materials, University of Manchester , Manchester M13 9PL, U.K
| | - Dursun Ekren
- School of Materials, University of Manchester , Manchester M13 9PL, U.K
| | | | - Marco Molinari
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K.,Department of Chemistry, University of Huddersfield , Huddersfield HD1 3DH, U.K
| | - Stephen C Parker
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus , Daresbury WA4 4AD, U.K
| | - Robert Freer
- School of Materials, University of Manchester , Manchester M13 9PL, U.K
| |
Collapse
|
46
|
Azough F, Jackson SS, Ekren D, Freer R, Molinari M, Yeandel SR, Panchmatia PM, Parker SC, Maldonado DH, Kepaptsoglou DM, Ramasse QM. Concurrent La and A-Site Vacancy Doping Modulates the Thermoelectric Response of SrTiO 3: Experimental and Computational Evidence. ACS Appl Mater Interfaces 2017; 9:41988-42000. [PMID: 29134804 DOI: 10.1021/acsami.7b14231] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
To help understand the factors controlling the performance of one of the most promising n-type oxide thermoelectric SrTiO3, we need to explore structural control at the atomic level. In Sr1-xLa2x/3TiO3 ceramics (0.0 ≤ x ≤ 0.9), we determined that the thermal conductivity can be reduced and controlled through an interplay of La-substitution and A-site vacancies and the formation of a layered structure. The decrease in thermal conductivity with La and A-site vacancy substitution dominates the trend in the overall thermoelectric response. The maximum dimensionless figure of merit is 0.27 at 1070 K for composition x = 0.50 where half of the A-sites are occupied with La and vacancies. Atomic resolution Z-contrast imaging and atomic scale chemical analysis show that as the La content increases, A-site vacancies initially distribute randomly (x < 0.3), then cluster (x ≈ 0.5), and finally form layers (x = 0.9). The layering is accompanied by a structural phase transformation from cubic to orthorhombic and the formation of 90° rotational twins and antiphase boundaries, leading to the formation of localized supercells. The distribution of La and A-site vacancies contributes to a nonuniform distribution of atomic scale features. This combination induces temperature stable behavior in the material and reduces thermal conductivity, an important route to enhancement of the thermoelectric performance. A computational study confirmed that the thermal conductivity of SrTiO3 is lowered by the introduction of La and A-site vacancies as shown by the experiments. The modeling supports that a critical mass of A-site vacancies is needed to reduce thermal conductivity and that the arrangement of La, Sr, and A-site vacancies has a significant impact on thermal conductivity only at high La concentration.
Collapse
Affiliation(s)
- Feridoon Azough
- School of Materials, University of Manchester , Manchester M13 9PL, U.K
| | - Samuel S Jackson
- School of Materials, University of Manchester , Manchester M13 9PL, U.K
| | - Dursun Ekren
- School of Materials, University of Manchester , Manchester M13 9PL, U.K
| | - Robert Freer
- School of Materials, University of Manchester , Manchester M13 9PL, U.K
| | - Marco Molinari
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
- Department of Chemistry, University of Huddersfield , Queensgate, Huddersfield HD1 3DH, U.K
| | - Stephen R Yeandel
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
- Department of Chemistry, Loughborough University , Epinal Way, Loughborough LE11 3TU, U.K
| | - Pooja M Panchmatia
- Department of Chemistry, Loughborough University , Epinal Way, Loughborough LE11 3TU, U.K
| | - Stephen C Parker
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | | | - Demie M Kepaptsoglou
- SuperSTEM Laboratory , SciTech Daresbury Campus, Keckwick Lane, Warrington WA4 4AD, U.K
| | - Quentin M Ramasse
- SuperSTEM Laboratory , SciTech Daresbury Campus, Keckwick Lane, Warrington WA4 4AD, U.K
| |
Collapse
|
47
|
Lord AM, Ramasse QM, Kepaptsoglou DM, Periwal P, Ross FM, Wilks SP. Stability of Schottky and Ohmic Au Nanocatalysts to ZnO Nanowires. Nano Lett 2017; 17:6626-6636. [PMID: 29024594 DOI: 10.1021/acs.nanolett.7b02561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Manufacturable nanodevices must now be the predominant goal of nanotechnological research to ensure the enhanced properties of nanomaterials can be fully exploited and fulfill the promise that fundamental science has exposed. Here, we test the electrical stability of Au nanocatalyst-ZnO nanowire contacts to determine the limits of the electrical transport properties and the metal-semiconductor interfaces. While the transport properties of as-grown Au nanocatalyst contacts to ZnO nanowires have been well-defined, the stability of the interfaces over lengthy time periods and the electrical limits of the ohmic or Schottky function have not been studied. In this work, we use a recently developed iterative analytical process that directly correlates multiprobe transport measurements with subsequent aberration-corrected scanning transmission electron microscopy to study the electrical, structural, and chemical properties when the nanowires are pushed to their electrical limits and show structural changes occur at the metal-nanowire interface or at the nanowire midshaft. The ohmic contacts exhibit enhanced quantum-mechanical edge-tunneling transport behavior because of additional native semiconductor material at the contact edge due to a strong metal-support interaction. The low-resistance nature of the ohmic contacts leads to catastrophic breakdown at the middle of the nanowire span where the maximum heating effect occurs. Schottky-type Au-nanowire contacts are observed when the nanowires are in the as-grown pristine state and display entirely different breakdown characteristics. The higher-resistance rectifying I-V behavior degrades as the current is increased which leads to a permanent weakening of the rectifying effect and atomic-scale structural changes at the edge of the Au interface where the tunneling current is concentrated. Furthermore, to study modified nanowires such as might be used in devices the nanoscale tunneling path at the interface edge of the ohmic nanowire contacts is removed with a simple etch treatment and the nanowires show similar I-V characteristics during breakdown as the Schottky pristine contacts. Breakdown is shown to occur either at the nanowire midshaft or at the Au contact depending on the initial conductivity of the Au contact interface. These results demonstrate the Au-nanowire structures are capable of withstanding long periods of electrical stress and are stable at high current densities ensuring they are ideal components for nanowire-device designs while providing the flexibility of choosing the electrical transport properties which other Au-nanowire systems cannot presently deliver.
Collapse
Affiliation(s)
- Alex M Lord
- Centre for NanoHealth, College of Engineering, University of Swansea , Singleton Park SA2 8PP, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, United Kingdom
| | - Despoina M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, United Kingdom
| | - Priyanka Periwal
- Department of Electrical Engineering, University of Cambridge , Cambridge CB0 3FA, United Kingdom
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States of America
| | - Frances M Ross
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States of America
| | - Steve P Wilks
- Multidisciplinary Nanotechnology Centre, Department of Physics, College of Science, University of Swansea , Singleton Park, SA2 8PP, United Kingdom
| |
Collapse
|
48
|
Furnival T, Leary RK, Tyo EC, Vajda S, Ramasse QM, Thomas JM, Bristowe PD, Midgley PA. Anomalous diffusion of single metal atoms on a graphene oxide support. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.04.071] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
49
|
Alexander JA, Scheltens FJ, Drummy LF, Durstock MF, Hage FS, Ramasse QM, McComb DW. High-resolution monochromated electron energy-loss spectroscopy of organic photovoltaic materials. Ultramicroscopy 2017; 180:125-132. [DOI: 10.1016/j.ultramic.2017.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 02/27/2017] [Accepted: 03/01/2017] [Indexed: 10/20/2022]
|
50
|
Ramasse QM. Twenty years after: How “Aberration correction in the STEM” truly placed a “A synchrotron in a Microscope”. Ultramicroscopy 2017; 180:41-51. [DOI: 10.1016/j.ultramic.2017.03.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 03/06/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
|