1
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Pouchlý V, Talimian A, Kaštyl J, Chvíla M, Ščasnovič E, Betlrán AM, Lozano JG, Galusek D. Transparent LiOH-Doped Magnesium Aluminate Spinel Produced by Spark Plasma Sintering: Effects of Heating Rate and Dopant Concentration. Ann Ital Chir 2023. [DOI: 10.1016/j.jeurceramsoc.2023.01.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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2
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Lozano JG, Dillon F, Naylor AJ, Lee LY, Lippard C, Johnstone D, Bruce PG, Grobert N. Single source precursor route to iron sulfide nanomaterials for energy storage. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2019.136993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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3
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House RA, Maitra U, Pérez-Osorio MA, Lozano JG, Jin L, Somerville JW, Duda LC, Nag A, Walters A, Zhou KJ, Roberts MR, Bruce PG. Superstructure control of first-cycle voltage hysteresis in oxygen-redox cathodes. Nature 2019; 577:502-508. [DOI: 10.1038/s41586-019-1854-3] [Citation(s) in RCA: 266] [Impact Index Per Article: 53.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 10/01/2019] [Indexed: 11/09/2022]
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4
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Liberti E, Lozano JG, Pérez Osorio MA, Roberts MR, Bruce PG, Kirkland AI. Quantifying oxygen distortions in lithium-rich transition-metal-oxide cathodes using ABF STEM. Ultramicroscopy 2019; 210:112914. [PMID: 31811959 DOI: 10.1016/j.ultramic.2019.112914] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/11/2019] [Accepted: 11/22/2019] [Indexed: 11/26/2022]
Abstract
Lithium-rich cathodes can store excess charge beyond the transition metal redox capacity by participation of oxygen in reversible anionic redox reactions. Although these processes are crucial for achieving high energy densities, their structural origins are not yet fully understood. Here, we explore the use of annular bright-field (ABF) imaging in scanning transmission electron microscopy (STEM) to measure oxygen distortions in charged Li1.2Ni0.2Mn0.6O2. We show that ABF STEM data can provide positional accuracies below 20 pm but this is restricted to cases where no specimen mistilt is present, and only for a range of thicknesses above 3.5 nm. The reliability of these measurements is compromised even when the experimental and post-processing designs are optimised for accuracy and precision, indicating that extreme care must be taken when attempting to quantify distortions in these materials.
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Affiliation(s)
- E Liberti
- Department of Materials, University of Oxford, Parks Road OX1 3PH, UK.
| | - J G Lozano
- Department of Materials, University of Oxford, Parks Road OX1 3PH, UK
| | - M A Pérez Osorio
- Department of Materials, University of Oxford, Parks Road OX1 3PH, UK
| | - M R Roberts
- Department of Materials, University of Oxford, Parks Road OX1 3PH, UK
| | - P G Bruce
- Department of Materials, University of Oxford, Parks Road OX1 3PH, UK
| | - A I Kirkland
- Department of Materials, University of Oxford, Parks Road OX1 3PH, UK
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5
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Piché D, Tavernaro I, Fleddermann J, Lozano JG, Varambhia A, Maguire ML, Koch M, Ukai T, Hernández Rodríguez AJ, Jones L, Dillon F, Reyes Molina I, Mitzutani M, González Dalmau ER, Maekawa T, Nellist PD, Kraegeloh A, Grobert N. Targeted T 1 Magnetic Resonance Imaging Contrast Enhancement with Extraordinarily Small CoFe 2O 4 Nanoparticles. ACS Appl Mater Interfaces 2019; 11:6724-6740. [PMID: 30688055 PMCID: PMC6385080 DOI: 10.1021/acsami.8b17162] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 01/28/2019] [Indexed: 06/09/2023]
Abstract
Extraordinarily small (2.4 nm) cobalt ferrite nanoparticles (ESCIoNs) were synthesized by a one-pot thermal decomposition approach to study their potential as magnetic resonance imaging (MRI) contrast agents. Fine size control was achieved using oleylamine alone, and annular dark-field scanning transmission electron microscopy revealed highly crystalline cubic spinel particles with atomic resolution. Ligand exchange with dimercaptosuccinic acid rendered the particles stable in physiological conditions with a hydrodynamic diameter of 12 nm. The particles displayed superparamagnetic properties and a low r2/ r1 ratio suitable for a T1 contrast agent. The particles were functionalized with bile acid, which improved biocompatibility by significant reduction of reactive oxygen species generation and is a first step toward liver-targeted T1 MRI. Our study demonstrates the potential of ESCIoNs as T1 MRI contrast agents.
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Affiliation(s)
- Dominique Piché
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Isabella Tavernaro
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Jana Fleddermann
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Juan G. Lozano
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Aakash Varambhia
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Mahon L. Maguire
- British
Heart Foundation Experimental Magnetic Resonance Unit, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, England
| | - Marcus Koch
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Tomofumi Ukai
- Bio-Nano
Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan
| | - Armando J. Hernández Rodríguez
- Departamento
de Imágenes por Resonancia Magnética, Cuban Neurosciences Center, Street 190 e/25 and 27, Cubanacan
Playa, Havana CP 11600, Cuba
| | - Lewys Jones
- Advanced
Microscopy Laboratory, Centre for Research
on Adaptive Nanostructures and Nanodevices (CRANN), Dublin 2, Ireland
- School of
Physics, Trinity College Dublin, Dublin 2, Ireland
| | - Frank Dillon
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Israel Reyes Molina
- Departamento
de Imágenes por Resonancia Magnética, Cuban Neurosciences Center, Street 190 e/25 and 27, Cubanacan
Playa, Havana CP 11600, Cuba
| | - Mai Mitzutani
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
- Department
of Material Science and Engineering, Tokyo
Institute of Technology, S8-25, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Evelio R. González Dalmau
- Departamento
de Imágenes por Resonancia Magnética, Cuban Neurosciences Center, Street 190 e/25 and 27, Cubanacan
Playa, Havana CP 11600, Cuba
| | - Toru Maekawa
- Bio-Nano
Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan
| | - Peter D. Nellist
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Annette Kraegeloh
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Nicole Grobert
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
- Williams Advanced Engineering, Grove, Oxfordshire, OX12
0DQ, England
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6
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Lozano JG, Martinez GT, Jin L, Nellist PD, Bruce PG. Low-Dose Aberration-Free Imaging of Li-Rich Cathode Materials at Various States of Charge Using Electron Ptychography. Nano Lett 2018; 18:6850-6855. [PMID: 30257093 DOI: 10.1021/acs.nanolett.8b02718] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Imaging the complete atomic structure of materials, including light elements, with minimal beam-induced damage of the sample is a long-standing challenge in electron microscopy. Annular bright-field scanning transmission electron microscopy is often used to image elements with low atomic numbers, but due to its low efficiency and high sensitivity to precise imaging parameters it comes at the price of potentially significant beam damage. In this paper, we show that electron ptychography is a powerful technique to retrieve reconstructed phase images that provide the full structure of beam-sensitive materials containing light and heavy elements. Due to its much higher efficiency, we can reduce the beam currents used down to the subpicoampere range. Electron ptychography also allows residual lens aberrations to be corrected at the postprocessing stage, which avoids the need for fine-tuning of the probe that would result in further beam damage and provides aberration-free reconstructed phase images. We have used electron ptychography to obtain structural information from aberration-free reconstructed phase images in the technologically relevant lithium-rich transition metal oxides at different states of charge. We can unambiguously determine the position of the lithium and oxygen atomic columns while amorphization of the surface, formation of beam-induced surface reconstruction layers, or migration of transition metals to the alkali layers are drastically reduced.
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Affiliation(s)
- Juan G Lozano
- Department of Materials , University of Oxford , Parks Road , OX1 3PH Oxford , United Kingdom
| | - Gerardo T Martinez
- Department of Materials , University of Oxford , Parks Road , OX1 3PH Oxford , United Kingdom
| | - Liyu Jin
- Department of Materials , University of Oxford , Parks Road , OX1 3PH Oxford , United Kingdom
| | - Peter D Nellist
- Department of Materials , University of Oxford , Parks Road , OX1 3PH Oxford , United Kingdom
| | - Peter G Bruce
- Department of Materials , University of Oxford , Parks Road , OX1 3PH Oxford , United Kingdom
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7
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Zhang W, Richter FH, Culver SP, Leichtweiss T, Lozano JG, Dietrich C, Bruce PG, Zeier WG, Janek J. Degradation Mechanisms at the Li 10GeP 2S 12/LiCoO 2 Cathode Interface in an All-Solid-State Lithium-Ion Battery. ACS Appl Mater Interfaces 2018; 10:22226-22236. [PMID: 29877698 DOI: 10.1021/acsami.8b05132] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
All-solid-state batteries (ASSBs) show great potential for providing high power and energy densities with enhanced battery safety. While new solid electrolytes (SEs) have been developed with high enough ionic conductivities, SSBs with long operational life are still rarely reported. Therefore, on the way to high-performance and long-life ASSBs, a better understanding of the complex degradation mechanisms, occurring at the electrode/electrolyte interfaces is pivotal. While the lithium metal/solid electrolyte interface is receiving considerable attention due to the quest for high energy density, the interface between the active material and solid electrolyte particles within the composite cathode is arguably the most difficult to solve and study. In this work, multiple characterization methods are combined to better understand the processes that occur at the LiCoO2 cathode and the Li10GeP2S12 solid electrolyte interface. Indium and Li4Ti5O12 are used as anode materials to avoid the instability problems associated with Li-metal anodes. Capacity fading and increased impedances are observed during long-term cycling. Postmortem analysis with scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy show that electrochemically driven mechanical failure and degradation at the cathode/solid electrolyte interface contribute to the increase in internal resistance and the resulting capacity fading. These results suggest that the development of electrochemically more stable SEs and the engineering of cathode/SE interfaces are crucial for achieving reliable SSB performance.
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Affiliation(s)
- Wenbo Zhang
- Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Felix H Richter
- Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
- Departments of Materials and Chemistry , University of Oxford , OX1 3PH Oxford , United Kingdom
| | - Sean P Culver
- Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Thomas Leichtweiss
- Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Juan G Lozano
- Departments of Materials and Chemistry , University of Oxford , OX1 3PH Oxford , United Kingdom
| | - Christian Dietrich
- Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Peter G Bruce
- Departments of Materials and Chemistry , University of Oxford , OX1 3PH Oxford , United Kingdom
| | - Wolfgang G Zeier
- Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Jürgen Janek
- Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
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8
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Meysami SS, Dallas P, Britton J, Lozano JG, Murdock AT, Ferraro C, Gutierrez ES, Rijnveld N, Holdway P, Porfyrakis K, Grobert N. Ultra-stiff large-area carpets of carbon nanotubes. Nanoscale 2016; 8:11993-12001. [PMID: 27240959 DOI: 10.1039/c6nr01660j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Herewith, we report the influence of post-synthesis heat treatment (≤2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm(2)) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, ≥4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes.
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Affiliation(s)
| | - Panagiotis Dallas
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
| | - Jude Britton
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
| | - Juan G Lozano
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
| | - Adrian T Murdock
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
| | - Claudio Ferraro
- Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | | | - Niek Rijnveld
- Optics11, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands
| | - Philip Holdway
- Oxford Materials Characterisation Service, Oxford University Begbroke Science Park, Yarnton, OX5 1PF, UK
| | - Kyriakos Porfyrakis
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
| | - Nicole Grobert
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
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9
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Yang H, Lozano JG, Pennycook TJ, Jones L, Hirsch PB, Nellist PD. Imaging screw dislocations at atomic resolution by aberration-corrected electron optical sectioning. Nat Commun 2015; 6:7266. [PMID: 26041257 PMCID: PMC4468905 DOI: 10.1038/ncomms8266] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [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: 12/15/2014] [Accepted: 04/23/2015] [Indexed: 11/10/2022] Open
Abstract
Screw dislocations play an important role in materials' mechanical, electrical and optical properties. However, imaging the atomic displacements in screw dislocations remains challenging. Although advanced electron microscopy techniques have allowed atomic-scale characterization of edge dislocations from the conventional end-on view, for screw dislocations, the atoms are predominantly displaced parallel to the dislocation line, and therefore the screw displacements are parallel to the electron beam and become invisible when viewed end-on. Here we show that screw displacements can be imaged directly with the dislocation lying in a plane transverse to the electron beam by optical sectioning using annular dark field imaging in a scanning transmission electron microscope. Applying this technique to a mixed [a+c] dislocation in GaN allows direct imaging of a screw dissociation with a 1.65-nm dissociation distance, thereby demonstrating a new method for characterizing dislocation core structures.
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Affiliation(s)
- H Yang
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, UK
| | - J G Lozano
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, UK
| | - T J Pennycook
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, UK.,EPSRC SuperSTEM Facility, STFC Daresbury, WA4 4AD, UK
| | - L Jones
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, UK
| | - P B Hirsch
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, UK
| | - P D Nellist
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, UK.,EPSRC SuperSTEM Facility, STFC Daresbury, WA4 4AD, UK
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10
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Lozano JG, Yang H, Guerrero-Lebrero MP, D'Alfonso AJ, Yasuhara A, Okunishi E, Zhang S, Humphreys CJ, Allen LJ, Galindo PL, Hirsch PB, Nellist PD. Direct observation of depth-dependent atomic displacements associated with dislocations in gallium nitride. Phys Rev Lett 2014; 113:135503. [PMID: 25302902 DOI: 10.1103/physrevlett.113.135503] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Indexed: 06/04/2023]
Abstract
We demonstrate that the aberration-corrected scanning transmission electron microscope has a sufficiently small depth of field to observe depth-dependent atomic displacements in a crystal. The depth-dependent displacements associated with the Eshelby twist of dislocations in GaN normal to the foil with a screw component of the Burgers vector are directly imaged. We show that these displacements are observed as a rotation of the lattice between images taken in a focal series. From the sense of the rotation, the sign of the screw component can be determined.
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Affiliation(s)
- J G Lozano
- Department of Materials, University of Oxford, OX1 3PH Oxford, United Kingdom
| | - H Yang
- Department of Materials, University of Oxford, OX1 3PH Oxford, United Kingdom
| | - M P Guerrero-Lebrero
- Departamento de Ingeniería Informática, CASEM, Universidad de Cadiz, Polígono Rio San Pedro s/n, 11510 Puerto Real (Cadiz), Spain
| | - A J D'Alfonso
- School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - A Yasuhara
- JEOL Ltd., 1-2 Musashino 3-Chome, Akishima, 196-8558 Tokyo, Japan
| | - E Okunishi
- JEOL Ltd., 1-2 Musashino 3-Chome, Akishima, 196-8558 Tokyo, Japan
| | - S Zhang
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, CB3 0FS Cambridge, United Kingdom
| | - C J Humphreys
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, CB3 0FS Cambridge, United Kingdom
| | - L J Allen
- School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - P L Galindo
- Departamento de Ingeniería Informática, CASEM, Universidad de Cadiz, Polígono Rio San Pedro s/n, 11510 Puerto Real (Cadiz), Spain
| | - P B Hirsch
- Department of Materials, University of Oxford, OX1 3PH Oxford, United Kingdom
| | - P D Nellist
- Department of Materials, University of Oxford, OX1 3PH Oxford, United Kingdom
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11
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González D, Lozano JG, Herrera M, Morales FM, Ruffenach S, Briot O, García R. Phase mapping of aging process in InN nanostructures: oxygen incorporation and the role of the zinc blende phase. Nanotechnology 2010; 21:185706. [PMID: 20388966 DOI: 10.1088/0957-4484/21/18/185706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Uncapped InN nanostructures undergo a deleterious natural aging process at ambient conditions by oxygen incorporation. The phases involved in this process and their localization is mapped by transmission electron microscopy (TEM)-related techniques. The parent wurtzite InN (InN-w) phase disappears from the surface and gradually forms a highly textured cubic layer that completely wraps up a InN-w nucleus which still remains from the original single-crystalline quantum dots. The good reticular relationships between the different crystals generate low misfit strains and explain the apparent easiness for phase transformations at room temperature and pressure conditions, but also disable the classical methods to identify phases and grains from TEM images. The application of the geometrical phase algorithm in order to form numerical moiré mappings and RGB multilayered image reconstructions allows us to discern among the different phases and grains formed inside these nanostructures. Samples aged for shorter times reveal the presence of metastable InN:O zinc blende (zb) volumes, which act as the intermediate phase between the initial InN-w and the most stable cubic In(2)O(3) end phase. These cubic phases are highly twinned with a proportion of 50:50 between both orientations. We suggest that the existence of the intermediate InN:O-zb phase should be seriously considered to understand the reason for the widely scattered reported fundamental properties of thought to be InN-w, as its bandgap or superconductivity.
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Affiliation(s)
- D González
- Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cádiz, Puerto Real, Cádiz 11510, Spain.
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12
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Lozano JG, Sánchez AM, García R, Ruffenach S, Briot O, González D. Strain Relief Analysis of InN Quantum Dots Grown on GaN. Nanoscale Res Lett 2007; 2:442-446. [PMID: 21794190 PMCID: PMC3246598 DOI: 10.1007/s11671-007-9080-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2007] [Accepted: 07/18/2007] [Indexed: 05/29/2023]
Abstract
We present a study by transmission electron microscopy (TEM) of the strain state of individual InN quantum dots (QDs) grown on GaN substrates. Moiré fringe and high resolution TEM analyses showed that the QDs are almost fully relaxed due to the generation of a 60° misfit dislocation network at the InN/GaN interface. By applying the Geometric Phase Algorithm to plan-view high-resolution micrographs, we show that this network consists of three essentially non-interacting sets of misfit dislocations lying along the directions. Close to the edge of the QD, the dislocations curve to meet the surface and form a network of threading dislocations surrounding the system.
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Affiliation(s)
- Juan G Lozano
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, 11510, Puerto Real, Cadiz, Spain.
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13
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Affiliation(s)
- J G Lozano
- Servicio de Radiologia, Hospital Valle del Nalon, Asturias, Spain
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14
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Santana-Penín U, Lozano JG. An accurate method for occlusal registration and altered-cast impression for removable partial dentures during the same visit as the framework try-in. J Prosthet Dent 1998; 80:615-8. [PMID: 9813814 DOI: 10.1016/s0022-3913(98)70040-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Preparation of mandibular distal-extension removable partial dentures usually requires a secondary impression (the altered-cast impression) to improve the stability of the prosthesis. A potential problem with conventional altered-cast impression procedures is incorrect or incomplete seating of the framework in the mouth or on the cast. This article describes a procedure for obtaining the interjaw relationship and an accurate altered-cast impression in a single appointment (that of the framework try-in).
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Affiliation(s)
- U Santana-Penín
- Faculty of Medicine and Odontology, University of Santiago de Compostela, Spain
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