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629 results on '"Lupini A. R."'

158. Controlling hydrocarbon transport and electron beam induced deposition on single layer graphene: Toward atomic scale synthesis in the scanning transmission electron microscope.

Author

Dyck, Ondrej, Lupini, Andrew R., Rack, Philip D., Fowlkes, Jason, and Jesse, Stephen

Subjects
HYDROCARBONS, ELECTRON beams, SCANNING transmission electron microscopy, THREE-dimensional printing, GRAPHENE
Abstract

Focused electron beam induced deposition (FEBID) is a direct write technique for depositing materials on a support substrate akin to 3D printing with an electron beam (e‐beam). Opportunities exist for merging this existing technique with aberration‐corrected scanning transmission electron microscopy to achieve molecular‐ or atomic‐level spatial precision. Several demonstrations have been performed using graphene as the support substrate. A common challenge that arises during this process is e‐beam‐induced hydrocarbon deposition, suggesting greater control over the sample environment is needed. Various strategies exist for cleaning graphene in situ. One of the most effective methods is to rapidly heat to high temperatures, for example, 600℃ or higher. While this can produce large areas of what appears to be atomically clean graphene, mobile hydrocarbons can still be present on the surfaces. Here, we show that these hydrocarbons are primarily limited to surface migration and demonstrate an effective method for interrupting the flow using e‐beam deposition to form corralled hydrocarbon regions. This strategy is effective for maintaining atomically clean graphene at high temperatures where hydrocarbon mobility can lead to substantial accumulation of unwanted e‐beam deposition. [ABSTRACT FROM AUTHOR]

Published
2022
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160. Direct Sub-Angstrom Imaging of a Crystal Lattice

Author

Nellist, P. D., Chisholm, M. F., Dellby, N., Krivanek, O. L., Murfitt, M. F., Szilagyi, Z. S., Lupini, A. R., Borisevich, A., Sides, W. H., Jr., and Pennycook, S. J.

Published
2004

166. Atom-by-atom fabrication with electron beams

Author

Dyck, Ondrej, primary, Ziatdinov, Maxim, additional, Lingerfelt, David B., additional, Unocic, Raymond R., additional, Hudak, Bethany M., additional, Lupini, Andrew R., additional, Jesse, Stephen, additional, and Kalinin, Sergei V., additional

Published
2019
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169. Aberration-corrected scanning transmission electron microscopy: the potential for nano- and interface science

Author

Pennycook, S. J., Lupini, A. R., Kadavanich, A., McBride, J. R., Rosenthal, S. J., Puetter, R. C., Yahil, A., Krivanek, O. L., Dellby, N., Nellist, P.D.L., Duscher, G., Wang, L. G., and Pantelides, S. T.

Abstract

The sub-Ångström probe of an aberration-corrected scanning transmission electron microscope will enable imaging and analysis of nanostructures and interfaces with unprecedented resolution and sensitivity. In conjunction with first-principles theory, new insights are anticipated into the atomistic processes of growth and the subtle link between structure and functionality. We present initial results from the aberration-corrected microscopes at Oak Ridge National Laboratory that indicate the kinds of studies that will become feasible in the near future. Examples include (1) the three-dimensional location and identification of individual dopant and impurity atoms in semiconductor interfaces, and their effect on local electronic structure; (2) the accurate reconstruction of surface atomic and electronic structure on nanocrystals, and the effect on optical properties; and (3) the ability to distinguish which configurations of catalyst atoms are active, and why.

Published
2022
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171. Atomic Structure of the Initial Nucleation Layer in Hexagonal Perovskite BaRuO3 Thin Films.

Author

Yoon, Sangmoon, Ok, Jong Mok, Lee, Sang A, Lee, Jegon, Huon, Amanda, Lupini, Andrew R., Choi, Woo Seok, and Lee, Ho Nyung

Subjects
THIN films, ATOMIC structure, NUCLEATION, PEROVSKITE, EPITAXY, SCANNING transmission electron microscopy
Abstract

Hexagonal perovskites are an attractive family of materials due to their various polymorphs and rich structure–property relationships. BaRuO3 (BRO) is a prototypical hexagonal perovskite, in which the electromagnetic properties are significantly modified depending on its lattice structure. Whereas thin‐film synthesis would allow the study of the diverse properties of hexagonal perovskites by epitaxially stabilizing various metastable polymorphs, the epitaxial growth of hexagonal perovskites, especially at the initial growth stage, is yet to be addressed. In this study, it is shown that an intriguing nucleation behavior takes place during the initial stabilization of a hexagonal 9R BRO thin film deposited on a (111) SrTiO3 (STO) substrate. It is found that a nanoscale strained layer composed of different RuO6 octahedral stacking is initially formed at the interface followed by a relaxed single crystal 9R BRO thin film. Within the interface layer, hexagonal BRO is nucleated on the (111) STO substrate by both face‐ and corner‐sharing octahedra. More interestingly, it is found that boundaries between differently stacked nucleation layers (heterostructural boundaries) facilitate strain relaxation, in addition to the formation of conventional misfit dislocations evolved from homostructural boundaries. The observations reveal an important underlying mechanism to understand the thin‐film epitaxy and strain accommodation in hexagonal perovskites. [ABSTRACT FROM AUTHOR]

Published
2021
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174. Towards Atomic-Scale Fabrication in Silicon

Author

Hudak, Bethany M., primary, Jesse, Stephen, additional, Song, Jiaming, additional, Borisevich, Albina, additional, Snijders, Paul C., additional, Kalinin, Sergei V., additional, and Lupini, Andrew R., additional

Published
2018
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176. Direct Imaging of Low-Dimensional Nanostructures

Author

Lupini, Andrew R., primary, Hudak, Bethany M., additional, Song, Jiaming, additional, Sims, Hunter, additional, Sharma, Yogesh, additional, Ward, T. Zac, additional, Pantelides, Sokrates T., additional, and Snijders, Paul C., additional

Published
2018
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178. Directed Atom-by-Atom Assembly of Dopants in Silicon

Author

Hudak, Bethany M., primary, Song, Jiaming, additional, Sims, Hunter, additional, Troparevsky, M. Claudia, additional, Humble, Travis S., additional, Pantelides, Sokrates T., additional, Snijders, Paul C., additional, and Lupini, Andrew R., additional

Published
2018
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179. Direct atomic fabrication and dopant positioning in Si using electron beams with active real-time image-based feedback

Author

Jesse, Stephen, primary, Hudak, Bethany M, additional, Zarkadoula, Eva, additional, Song, Jiaming, additional, Maksov, Artem, additional, Fuentes-Cabrera, Miguel, additional, Ganesh, Panchapakesan, additional, Kravchenko, Ivan, additional, Snijders, Paul C, additional, Lupini, Andrew R, additional, Borisevich, Albina Y, additional, and Kalinin, Sergei V, additional

Published
2018
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182. Structure and ultrafast dynamics of white-light-emitting CdSe nanocrystals

Author

Bowers, Michael J., II, McBride, James R., Garrett, Maria D., Sammons, Jessica A., Dukes, Albert D., III, Schreuder, Michael A., Watt, Tony L., Lupini, Andrew R., Pennycook, Stephen J., and Rosenthal, Sandra J.

Subjects
Selenium compounds -- Optical properties, Selenium compounds -- Spectra, Scanning tunneling microscopy -- Usage, Nanocrystals -- Research, Chemistry
Abstract

The first images of the structure of white-light emitting ultrasmall CdSe nanocrystals are obtained by using aberration-corrected atomic number contrast scanning transmission electron microscopy (Z-STEM). The exciton dynamics are measured at different wavelengths of the white-light spectrum by using ultrafast fluorescence upconversion spectroscopy, which has suggested that a myriad of trap states are responsible for the broad-spectrum emission.

Published
2009

183. Homo-endotaxial one-dimensional Si nanostructures

Author

Song, Jiaming, primary, Hudak, Bethany M., additional, Sims, Hunter, additional, Sharma, Yogesh, additional, Ward, T. Zac, additional, Pantelides, Sokrates T., additional, Lupini, Andrew R., additional, and Snijders, Paul C., additional

Published
2018
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184. Preparation and comparison of supported gold nanocatalysts on anatase, brookite, rutile, and P25 polymorphs of TiO2 for catalytic oxidation of CO

Author

Wenfu Yan, Bei Chen, Mahurin, S.M., Schwartz, V., Mullins, D.R., Lupini, Andrew R., Pennycook, S.J., Sheng Dai, and Overbury, S.H.

Subjects
Oxidation-reduction reaction -- Research, Gold -- Chemical properties, Titanium dioxide -- Chemical properties, Carbon monoxide -- Chemical properties, Carbon monoxide -- Research, Chemicals, plastics and rubber industries
Abstract

Nanosized anatase, rutile, and brookite titania particles are successfully synthesized through sonication and hydrothermal methods. The results indicate that the gold particles supported on brookite are smaller than those on the other supports following the reaction and pretreatment sequences.

Published
2005

188. Probing Strain-Induced Phenomena in Low Dimensionality Multiferroic Oxides

Author

Magen, C., primary, Guzman, R., additional, Farokhipoor, S., additional, Maurel, L., additional, Langenberg, E., additional, Iniguez, J., additional, Venkatesan, S., additional, Lupini, Andrew R., additional, Snoeck, E., additional, Mostovoy, M., additional, Algarabel, P. A., additional, Pardo, J. A., additional, and Noheda, B., additional

Published
2017
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194. Local electronic structure variation resulting in Li ‘filament’ formation within solid electrolytes

Author

Liu, Xiaoming, Garcia-Mendez, Regina, Lupini, Andrew R., Cheng, Yongqiang, Hood, Zachary D., Han, Fudong, Sharafi, Asma, Idrobo, Juan Carlos, Dudney, Nancy J., Wang, Chunsheng, Ma, Cheng, Sakamoto, Jeff, and Chi, Miaofang

Abstract

Solid electrolytes hold great promise for enabling the use of Li metal anodes. The main problem is that during cycling, Li can infiltrate along grain boundaries and cause short circuits, resulting in potentially catastrophic battery failure. At present, this phenomenon is not well understood. Here, through electron microscopy measurements on a representative system, Li7La3Zr2O12, we discover that Li infiltration in solid oxide electrolytes is strongly associated with local electronic band structure. About half of the Li7La3Zr2O12grain boundaries were found to have a reduced bandgap, around 1–3 eV, making them potential channels for leakage current. Instead of combining with electrons at the cathode, Li+ions are hence prematurely reduced by electrons at grain boundaries, forming local Li filaments. The eventual interconnection of these filaments results in a short circuit. Our discovery reveals that the grain-boundary electronic conductivity must be a primary concern for optimization in future solid-state battery design.

Published
2021
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195. Scanning Transmission Electron Microscopy

Author

Lupini, A. R., Rashkeev, S. N., Maria Varela, Borisevich, A. Y., Oxley, M. P., Benthem, K., Peng, Y., Jonge, N., Veith, G. M., Pennycook, T. J., Zhou, W., Ishikawa, R., Chisholm, M. F., Pantelides, S. T., and Pennycook, S. J.

Abstract

The scanning transmission electron microscope (STEM) is one of the most useful tools in many areas of atomic-scale materials science and nanocharacterization. A STEM has the ability to generate local maps of the chemical composition and electronic structure at atomic resolution, even in complex or unknown samples. Here we describe the important components of a state-of-the-art aberration-corrected STEM and review the application of STEM imaging to a variety of published nanocharacterisation examples in catalysis and solid state materials problems.

Published
2015
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199. Armor for Steel: Facile Synthesis of Hexagonal Boron Nitride Films on Various Substrates (Adv. Mater. Interfaces 1/2024).

Author

Vlassiouk, Ivan, Smirnov, Sergei, Puretzky, Alexander, Olunloyo, Olugbenga, Geohegan, David B., Dyck, Ondrej, Lupini, Andrew R., Unocic, Raymond R., Meyer, Harry M., Xiao, Kai, Briggs, Dayrl, Lavrik, Nickolay, Keum, Jong, Cakmak, Ercan, Harris, Sumner B., Checa, Marti, Collins, Liam, Lasseter, John, Emery, Reece, and Rayle, John

Subjects
STEEL, BORON nitride, ALUMINUM alloys, METALLIC films, SINGLE crystals, PROTECTIVE coatings
Published
2024
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