Records |
Author |
Susi, T.; Madsen, J.; Ludacka, U.; Mortensen, J.J.; Pennycook, T.J.; Lee, Z.; Kotakoski, J.; Kaiser, U.; Meyer, J.C. |
Title |
Efficient first principles simulation of electron scattering factors for transmission electron microscopy |
Type |
A1 Journal article |
Year |
2019 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
197 |
Issue |
197 |
Pages |
16-22 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Electron microscopy is a powerful tool for studying the properties of materials down to their atomic structure. In many cases, the quantitative interpretation of images requires simulations based on atomistic structure models. These typically use the independent atom approximation that neglects bonding effects, which may, however, be measurable and of physical interest. Since all electrons and the nuclear cores contribute to the scattering potential, simulations that go beyond this approximation have relied on computationally highly demanding all-electron calculations. Here, we describe a new method to generate ab initio electrostatic potentials when describing the core electrons by projector functions. Combined with an interface to quantitative image simulations, this implementation enables an easy and fast means to model electron scattering. We compare simulated transmission electron microscopy images and diffraction patterns to experimental data, showing an accuracy equivalent to earlier all-electron calculations at a much lower computational cost. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000456311700003 |
Publication Date |
2018-11-12 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue ![sorted by Series Issue field, ascending order (up)](img/sort_asc.gif) |
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Edition |
|
ISSN |
0304-3991 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.843 |
Times cited |
3 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: 2.843 |
Call Number |
UA @ admin @ c:irua:165938 |
Serial |
6296 |
Permanent link to this record |
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Author |
Leuthner, G.T.; Hummel, S.; Mangler, C.; Pennycook, T.J.; Susi, T.; Meyer, J.C.; Kotakoski, J. |
Title |
Scanning transmission electron microscopy under controlled low-pressure atmospheres |
Type |
A1 Journal article |
Year |
2019 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
203 |
Issue |
203 |
Pages |
76-81 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Transmission electron microscopy (TEM) is carried out in vacuum to minimize the interaction of the imaging electrons with gas molecules while passing through the microscope column. Nevertheless, in typical devices, the pressure remains at 10(-7) mbar or above, providing a large number of gas molecules for the electron beam to crack, which can lead to structural changes in the sample. Here, we describe experiments carried out in a modified scanning TEM (STEM) instrument, based on the Nion UltraSTEM 100. In this instrument, the base pressure at the sample is around 2 x 10(-10 )mbar, and can be varied up to 10(-6) mbar through introduction of gases directly into the objective area while maintaining atomic resolution imaging conditions. We show that air leaked into the microscope column during the experiment is efficient in cleaning graphene samples from contamination, but ineffective in damaging the pristine lattice. Our experiments also show that exposure to O(2 )and H2O lead to a similar result, oxygen providing an etching effect nearly twice as efficient as water, presumably due to the two 0 atoms per molecule. H(2 )and N-2 environments have no influence on etching. These results show that the residual gas environment in typical TEM instruments can have a large influence on the observations, and show that chemical etching of carbon-based structures can be effectively carried out with oxygen. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000465021000010 |
Publication Date |
2019-02-04 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue ![sorted by Series Issue field, ascending order (up)](img/sort_asc.gif) |
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Edition |
|
ISSN |
0304-3991 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.843 |
Times cited |
4 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: 2.843 |
Call Number |
UA @ admin @ c:irua:165937 |
Serial |
6321 |
Permanent link to this record |
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|
|
Author |
Madsen, J.; Pennycook, T.J.; Susi, T. |
Title |
ab initio description of bonding for transmission electron microscopy |
Type |
A1 Journal article |
Year |
2021 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
231 |
Issue |
|
Pages |
|
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
The simulation of transmission electron microscopy (TEM) images or diffraction patterns is often required to interpret their contrast and extract specimen features. This is especially true for high-resolution phase-contrast imaging of materials, but electron scattering simulations based on atomistic models are widely used in materials science and structural biology. Since electron scattering is dominated by the nuclear cores, the scattering potential is typically described by the widely applied independent atom model. This approximation is fast and fairly accurate, especially for scanning TEM (STEM) annular dark-field contrast, but it completely neglects valence bonding and its effect on the transmitting electrons. However, an emerging trend in electron microscopy is to use new instrumentation and methods to extract the maximum amount of information from each electron. This is evident in the increasing popularity of techniques such as 4D-STEM combined with ptychography in materials science, and cryogenic microcrystal electron diffraction in structural biology, where subtle differences in the scattering potential may be both measurable and contain additional insights. Thus, there is increasing interest in electron scattering simulations based on electrostatic potentials obtained from first principles, mainly via density functional theory, which was previously mainly required for holography. In this Review, we discuss the motivation and basis for these developments, survey the pioneering work that has been published thus far, and give our outlook for the future. We argue that a physically better justified ab initio description of the scattering potential is both useful and viable for an increasing number of systems, and we expect such simulations to steadily gain in popularity and importance. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000744190300006 |
Publication Date |
2021-03-18 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue ![sorted by Series Issue field, ascending order (up)](img/sort_asc.gif) |
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Edition |
|
ISSN |
0304-3991 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.843 |
Times cited |
|
Open Access |
OpenAccess |
Notes |
|
Approved |
Most recent IF: 2.843 |
Call Number |
UA @ admin @ c:irua:183955 |
Serial |
6850 |
Permanent link to this record |
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Author |
Mustonen, K.; Hofer, C.; Kotrusz, P.; Markevich, A.; Hulman, M.; Mangler, C.; Susi, T.; Pennycook, T.J.; Hricovini, K.; Richter, C.M.; Meyer, J.C.; Kotakoski, J.; Skákalová, V. |
Title |
Towards Exotic Layered Materials: 2D Cuprous Iodide |
Type |
A1 Journal article |
Year |
2021 |
Publication |
Advanced materials |
Abbreviated Journal |
Adv Mater |
Volume |
|
Issue |
|
Pages |
2106922 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
Heterostructures composed of two-dimensional (2D) materials are already opening many new possibilities in such fields of technology as electronics and magnonics, but far more could be achieved if the number and diversity of 2D materials is increased. So far, only a few dozen 2D crystals have been extracted from materials that exhibit a layered phase in ambient conditions, omitting entirely the large number of layered materials that may exist in other temperatures and pressures. Here, we demonstrate how these structures can be stabilized in 2D van der Waals stacks under room temperature via growing them directly in graphene encapsulation by using graphene oxide as the template material. Specifically, we produce an ambient stable 2D structure of copper and iodine, a material that normally only occurs in layered form at elevated temperatures between 645 and 675 K. Our results establish a simple route to the production of more exotic phases of materials that would otherwise be difficult or impossible to stabilize for experiments in ambient. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000744012500001 |
Publication Date |
2021-12-07 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue ![sorted by Series Issue field, ascending order (up)](img/sort_asc.gif) |
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Edition |
|
ISSN |
0935-9648 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
19.791 |
Times cited |
|
Open Access |
OpenAccess |
Notes |
We acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme Grant agreements No.~756277-ATMEN (A.M. and T.S.) and No.802123-HDEM (C.H. and T.J.P.). Computational resources from the Vienna Scientific Cluster (VSC) are gratefully acknowledged. V.S. was supported by the Austrian Science Fund (FWF) (project no. I2344-N36), the Slovak Research and Development Agency (APVV-16-0319), the project CEMEA of the Slovak Academy of Sciences, ITMS project code 313021T081 of the Research & Innovation Operational Programme and from the V4-Japan Joint Research Program (BGapEng). J.K. acknowledges the FWF funding within project P31605-N36 and M.H. the funding from Slovak Research and Development Agency via the APVV-15-0693 and APVV-19-0365 project grants. Danubia NanoTech s.r.o. has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101008099 (CompSafeNano project) and also thanks Mr. Kamil Bernath for his support. |
Approved |
Most recent IF: 19.791 |
Call Number |
EMAT @ emat @c:irua:183956 |
Serial |
6834 |
Permanent link to this record |