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985 results on '"Botton, Gianluigi A."'

2. Defect free strain relaxation of microcrystals on mesoporous patterned silicon

Author

Heintz, Alexandre, Ilahi, Bouraoui, Pofelski, Alexandre, Botton, Gianluigi, Patriarche, Gilles, Barzaghi, Andrea, Fafard, Simon, Arès, Richard, Isella, Giovanni, and Boucherif, Abderraouf

Subjects
Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

A perfectly compliant substrate would allow the monolithic integration of high-quality semiconductor materials such as Ge and III-V on Silicon (Si) substrate, enabling novel functionalities on the well-established low-cost Si technology platform. Here, we demonstrate a compliant Si substrate allowing defect-free epitaxial growth of lattice mismatched materials. The method is based on the deep patterning of the Si substrate to form micrometer-scale pillars and subsequent electrochemical porosification. The investigation of the epitaxial Ge crystalline quality by X-ray diffraction, transmission electron microscopy and etch-pits counting demonstrates the full elastic relaxation of defect-free microcrystals. The achievement of dislocation free heteroepitaxy relies on the interplay between elastic deformation of the porous micropillars, set under stress by the lattice mismatch between Ge and Si, and on the diffusion of Ge into the mesoporous patterned substrate attenuating the mismatch strain at the Ge/Si interface., Comment: 27 pages and 4 figures along with 11 figures in supplementary information

Published
2022
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3. Pnictogens Allotropy and Phase Transformation during van der Waals Growth

Author

Fortin-Deschênes, Matthieu, Zschiesche, Hannes, Menteş, Tevfik O., Locatelli, Andrea, Jacobberger, Robert M., Genuzio, Francesca, Lagos, Maureen J., Biswas, Deepnarayan, Jozwiak, Chris, Miwa, Jill A., Ulstrup, Søren, Bostwick, Aaron, Rotenberg, Eli, Arnold, Michael S., Botton, Gianluigi A., and Moutanabbir, Oussama

Subjects
Condensed Matter - Materials Science
Abstract

Pnictogens have multiple allotropic forms resulting from their ns2 np3 valence electronic configuration, making them the only elemental materials to crystallize in layered van der Waals (vdW) and quasi-vdW structures throughout the group. Light group VA elements are found in the layered orthorhombic A17 phase such as black phosphorus, and can transition to the layered rhombohedral A7 phase at high pressure. On the other hand, bulk heavier elements are only stable in the A7 phase. Herein, we demonstrate that these two phases not only co-exist during the vdW growth of antimony on weakly interacting surfaces, but also undertake a spontaneous transformation from the A17 phase to the thermodynamically stable A7 phase. This metastability of the A17 phase is revealed by real-time studies unraveling its thickness-driven transition to the A7 phase and the concomitant evolution of its electronic properties. At a critical thickness of ~4 nm, A17 antimony undergoes a diffusionless shuffle transition from AB to AA stacked alpha-antimonene followed by a gradual relaxation to the A7 bulk-like phase. Furthermore, the electronic structure of this intermediate phase is found to be determined by surface self-passivation and the associated competition between A7- and A17-like bonding in the bulk. These results highlight the critical role of the atomic structure and interfacial interactions in shaping the stability and electronic characteristics of vdW layered materials, thus enabling a new degree of freedom to engineer their properties using scalable processes.

Published
2020
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5. Publisher Correction: Copper adparticle enabled selective electrosynthesis of n-propanol.

Author

Li, Jun, Che, Fanglin, Pang, Yuanjie, Zou, Chengqin, Howe, Jane Y, Burdyny, Thomas, Edwards, Jonathan P, Wang, Yuhang, Li, Fengwang, Wang, Ziyun, De Luna, Phil, Dinh, Cao-Thang, Zhuang, Tao-Tao, Saidaminov, Makhsud I, Cheng, Shaobo, Wu, Tianpin, Finfrock, Y Zou, Ma, Lu, Hsieh, Shang-Hsien, Liu, Yi-Sheng, Botton, Gianluigi A, Pong, Way-Faung, Du, Xiwen, Guo, Jinghua, Sham, Tsun-Kong, Sargent, Edward H, and Sinton, David

Abstract

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Published
2020

6. Atomic-scale identification of novel planar defect phases in heteroepitaxial YBa$_2$Cu$_3$O$_{7-\delta}$ thin films

Author

Gauquelin, Nicolas, Zhang, Hao, Zhu, Guozhen, Wei, John Y. T., and Botton, Gianluigi A.

Subjects
Condensed Matter - Superconductivity
Abstract

We have discovered two novel types of planar defects that appear in heteroepitaxial YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO123) thin films, grown by pulsed-laser deposition (PLD) either with or without a La$_{2/3}$Ca$_{1/3}$MnO$_3$ (LCMO) overlayer, using the combination of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and electron energy loss spectroscopy (EELS) mapping for unambiguous identification. These planar lattice defects are based on the intergrowth of either a BaO plane between two CuO chains or multiple Y-O layers between two CuO$_2$ planes, resulting in non-stoichiometric layer sequences that could directly impact the high-$T_c$ superconductivity.

Published
2017

9. Copper adparticle enabled selective electrosynthesis of n-propanol.

Author

Li, Jun, Che, Fanglin, Pang, Yuanjie, Zou, Chengqin, Howe, Jane Y, Burdyny, Thomas, Edwards, Jonathan P, Wang, Yuhang, Li, Fengwang, Wang, Ziyun, De Luna, Phil, Dinh, Cao-Thang, Zhuang, Tao-Tao, Saidaminov, Makhsud I, Cheng, Shaobo, Wu, Tianpin, Finfrock, Y Zou, Ma, Lu, Hsieh, Shang-Hsien, Liu, Yi-Sheng, Botton, Gianluigi A, Pong, Way-Faung, Du, Xiwen, Guo, Jinghua, Sham, Tsun-Kong, Sargent, Edward H, and Sinton, David

Subjects
MD Multidisciplinary
Abstract

The electrochemical reduction of carbon monoxide is a promising approach for the renewable production of carbon-based fuels and chemicals. Copper shows activity toward multi-carbon products from CO reduction, with reaction selectivity favoring two-carbon products; however, efficient conversion of CO to higher carbon products such as n-propanol, a liquid fuel, has yet to be achieved. We hypothesize that copper adparticles, possessing a high density of under-coordinated atoms, could serve as preferential sites for n-propanol formation. Density functional theory calculations suggest that copper adparticles increase CO binding energy and stabilize two-carbon intermediates, facilitating coupling between adsorbed *CO and two-carbon intermediates to form three-carbon products. We form adparticle-covered catalysts in-situ by mediating catalyst growth with strong CO chemisorption. The new catalysts exhibit an n-propanol Faradaic efficiency of 23% from CO reduction at an n-propanol partial current density of 11 mA cm-2.

Published
2018

12. The effects of bending on plasmonic modes in nanowires and planar structures

Author

Bellido Edson P., Bicket Isobel C., and Botton Gianluigi A.

Subjects
antennas, coupling, eels, hybridization, nanowires, plasmonics, Physics, QC1-999
Abstract

In this work, we investigate the effects of bends on the surface plasmon resonances in nanowires (NWs) and isolated edges of planar structures using electron energy loss spectroscopy experiments and theoretical calculations. Previous work showed that the sharp bends in NWs do not affect their resonant modes. Here, we study previously overlooked effects and analyze systematically the evolution of resonant modes for several bending angles from 30° to 180°, showing that bending can have a significant effect on the plasmonic response of a nanostructure. In NWs, the modes can experience significant energy shifts that depend on the aspect ratio of the NW and can cause mode intersection and antinode bunching. We establish the relation between NW modes and edge modes and show that bending can even induce antinode splitting in edge modes. This work demonstrates that bends in plasmonic planar nanostructures can have a profound effect on their optical response and this must be accounted for in the design of optical devices.

Published
2021
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15. Real-space mapping of electronic orbitals

Author

Löffler, Stefan, Bugnet, Matthieu, Gauquelin, Nicolas, Lazar, Sorin, Assmann, Elias, Held, Karsten, Botton, Gianluigi A., and Schattschneider, Peter

Subjects
Condensed Matter - Materials Science
Abstract

Electronic states are responsible for most material properties, including chemical bonds, electrical and thermal conductivity, as well as optical and magnetic properties. Experimentally, however, they remain mostly elusive. Here, we report the real-space mapping of selected transitions between p and d states on the {\AA}ngstr\"om scale in bulk rutile (TiO2) using electron energy-loss spectrometry (EELS), revealing information on individual bonds between atoms. On the one hand, this enables the experimental verification of theoretical predictions about electronic states. On the other hand, it paves the way for directly investigating electronic states under conditions that are at the limit of the current capabilities of numerical simulations such as, e.g., the electronic states at defects, interfaces, and quantum dots.

Published
2016
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18. Binding Angle Robustness of Plasmonic Nanorod Dimer Resonances.

Author

Hohenau, Andreas, Bugnet, Matthieu, Kapetanovic, Viktor, Radtke, Guillaume, Botton, Gianluigi A., Reichelt, Nikita, Hohenester, Ulrich, Krenn, Joachim R., Boubekeur‐Lecaque, Leïla, and Félidj, Nordin

Subjects
TRANSMISSION electron microscopes, ELECTRON spectroscopy, NANORODS, SCANNING electron microscopes, DELOCALIZATION energy, ELECTRON energy loss spectroscopy
Abstract

Narrow gaps between coupled plasmonic nano‐particles show strong optical field enhancements and spectrally adjustable resonance positions, making them attractive for surface enhanced spectroscopies. Gold nanorod dimers formed from nanorod solutions with narrow size distributions are intensely investigated in this context. However, the binding angle of rods coupled at their end faces is usually not controllable. Surprisingly, it is observed that this has only little effect on field enhancement and resonance energies. In this work, gold nanorod dimers are investigated by mapping their plasmon resonances using electron energy‐loss spectroscopy in a scanning transmission electron microscope. For a wide range of dimer orientations, a negligible influence of the angle between the two rods on the bonding and antibonding longitudinal dipole resonances is confirmed, in good agreement with numerical simulations. The results are interpreted via the predominant end‐coupling of the individual nanorod's plasmonic modes, as illustrated by an analytical charge coupling model. In addition, the simulations emphasize that conclusions from experimental data on the gap morphology on the size range of one nanometer can be ambiguous. In any case, the full understanding of the angle‐invariant resonances of nano‐rod dimers can further promote their controlled application in surface enhanced spectroscopy or ‐sensing. [ABSTRACT FROM AUTHOR]

Published
2024
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20. A synergetic cocatalyst for conversion of carbon dioxide, sunlight, and water into methanol.

Author

Zhengwei Ye, Yang, Ke R., Bingxing Zhang, Navid, Ishtiaque Ahmed, Yifan Shen, Yixin Xiao, Pofelski, Alexandre, Botton, Gianluigi A., Tao Ma, Mondal, Shubham, Norris, Theodore B., Batista, Victor S., and Zetian Mi

Subjects
CARBON offsetting, LIQUID fuels, SUSTAINABILITY, CHROMIUM oxide, PHOTOREDUCTION
Abstract

The conversion of CO2 into liquid fuels, using only sunlight and water, offers a promising path to carbon neutrality. An outstanding challenge is to achieve high efficiency and product selectivity. Here, we introduce a wireless photocatalytic architecture for conversion of CO2 and water into methanol and oxygen. The catalytic material consists of semiconducting nanowires decorated with core-shell nanoparticles, with a copper-rhodium core and a chromium oxide shell. The Rh/CrOOH interface provides a unidirectional channel for proton reduction, enabling hydrogen spillover at the core-shell interface. The vectorial transfer of protons, electrons, and hydrogen atoms allows for switching the mechanism of CO2 reduction from a proton-coupled electron transfer pathway in aqueous solution to hydrogenation of CO2 with a solar-to-methanol efficiency of 0.22%. The reported findings demonstrate a highly efficient, stable, and scalable wireless system for synthesis of methanol from CO2 that could provide a viable path toward carbon neutrality and environmental sustainability. [ABSTRACT FROM AUTHOR]

Published
2024
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29. An Innovative Update and Expansion Programme to the UK’s National Synchrotron

Author

Botton, Gianluigi A., primary, Coll, Peter, additional, Dent, Andrew J., additional, Dhesi, Sarnjeet, additional, French, Sky, additional, Hall, David R., additional, Hriljac, Joseph, additional, MacDonell, Sarah, additional, Diaz-Moreno, Sofia, additional, Nicklin, Chris, additional, Quinn, Paul, additional, Rambo, Robert, additional, Sawhney, Kawal, additional, Walker, Richard P., additional, Walsh, Martin A., additional, and Pekarik-Fry, Molly, additional

Published
2024
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31. Epitaxial thin films of multiferroic Bi2FeCrO6 with B-site cationic order

Author

Nechache, Riad, Carignan, Louis-Philippe, Gunawan, Lina, Harnagea, Catalin, Botton, Gianluigi, Menard, David, and Pignolet, Alain

Subjects
Condensed Matter - Materials Science
Abstract

Epitaxial thin films of Bi2FeCrO6 have been synthesized by pulsed laser deposition on SrRuO3 on (100)- and (111)-oriented SrTiO3 substrates. Detailed X-ray diffraction and cross-section transmission electron microscopy analysis revealed a double perovskite crystal structure of the Bi2FeCrO6 epitaxial films very similar to that of BiFeO3 along with a particularly noteworthy Fe3+/Cr3+ cation ordering along the [111] direction. The films contain no detectable magnetic iron oxide impurities and have the correct cationic average stoichiometry throughout their thickness. They however exhibit a slight modulation in the Fe and Cr compositions forming complementary stripe patterns, suggesting minor local excess or depletion of Fe and Cr. The epitaxial BFCO films exhibit good ferroelectric and piezoelectric properties, in addition to magnetic properties at room temperature, as well as an unexpected crystallographic orientation dependence of their room temperature magnetic properties. Our results qualitatively confirm the predictions made using the ab-initio calculations: the double-perovskite structure of Bi2FeCrO6 films exhibit a Fe3+/Cr3+ cation ordering and good multiferroic properties, along with the unpredicted existence of magnetic ordering at room temperature., Comment: Accepted for publication in Journal of Materials Research

Published
2007
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34. Front Cover: Exploring the Synergistic Effects of Dual‐Layer Electrodes for High Power Li‐Ion Batteries (ChemElectroChem 21/2023)

Author

Dawkins, Jeremy I. G., primary, Pan, Yani, additional, Ghavidel, Mohammadreza Z., additional, Geissler, Johann, additional, Krueger, Bastian, additional, Chhin, Danny, additional, Yuan, Hui, additional, Tong, Victoria, additional, Pelletier‐Villeneuve, Brittany, additional, Feng, Renfei, additional, Botton, Gianluigi A., additional, Chapman, Karena W., additional, Mauzeroll, Janine, additional, and Schougaard, Steen B., additional

Published
2023
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35. Ga Desorption Kinetics in the Molecular Beam Epitaxy of AlGaN Nanowires for Ultrashort Wavelength Light-Emitting Diodes

Author

Zhang, Qihua, Yuan, Hui, Vafadar, Mohammad Fazel, Botton, Gianluigi A., and Zhao, Songrui

Abstract

In this work, we show that by growing AlGaN nanowires with molecular beam epitaxy (MBE) in a Ga highly desorbing regime, light-emitting diodes that can emit light at 209 nm are obtained. Detailed light emission characteristics and transmission electron microscopy studies indicate that such a light emission is due to the formation of AlN. The correlation between Ga desorption and electroluminescence (EL) is further investigated by using a unique approach with two different Al sources. It is found that the Ga desorption related to the surface-migrated Ga adatoms along the nanowire sidewall drastically affects the device EL properties, rather than the impinged Ga adatoms on the nanowire top surface. The unveiled correlation between the Ga desorption kinetics and EL properties could advance the development of technically important, ultrashort, wavelength-tunable semiconductor ultraviolet light-emitting diodes using AlGaN nanowires.

Published
2024
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42. Exploring the Synergistic Effects of Dual‐Layer Electrodes for High Power Li‐Ion Batteries.

Author

Dawkins, Jeremy I. G., Pan, Yani, Ghavidel, Mohammadreza Z., Geissler, Johann, Krueger, Bastian, Chhin, Danny, Yuan, Hui, Tong, Victoria, Pelletier‐Villeneuve, Brittany, Feng, Renfei, Botton, Gianluigi A., Chapman, Karena W., Mauzeroll, Janine, and Schougaard, Steen B.

Subjects
LITHIUM-ion batteries, ELECTRODE performance, ELECTRODES, X-ray fluorescence, ENERGY density, MANUFACTURING cells
Abstract

The electrification of the transport sector has created an increasing demand for lithium‐ion batteries that can provide high power intermittently while maintaining a high energy density. Given the difficulty in designing a single redox material with both high power and energy density, electrodes based on composites of several electroactive materials optimized for power or capacity are being studied extensively. Among others, fast‐charging LiFePO4 and high energy Li(NixMnyCoz)O2 are commonly employed in industrial cell manufacturing. This study focuses on comparing different approaches to combining these two active materials into a single electrode. These arrangements were compared using standard electrochemical (dis)charge procedures and using synchrotron X‐ray fluorescence to identify variations in solution concentration gradient formation. The electrochemical performance of the layered electrodes with the high‐power material on top is found to be enhanced relative to its blended electrode counterpart when (dis)charged at the same specific currents. These findings highlight dual‐layer lithium‐ion batteries as an inexpensive way of increasing energy and power density of lithium‐ion batteries as well as a model system to study and exploit the synergistic effects of blended electrodes. [ABSTRACT FROM AUTHOR]

Published
2023
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