Records |
Author |
Jones, L.; Yang, H.; Pennycook, T.J.; Marshall, M.S.J.; Van Aert, S.; Browning, N.D.; Castell, M.R.; Nellist, P.D. |
Title |
Smart Align : a new tool for robust non-rigid registration of scanning microscope data |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2015 |
Publication |
Advanced Structural and Chemical Imaging |
Abbreviated Journal |
|
Volume |
1 |
Issue |
1 |
Pages |
8 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Many microscopic investigations of materials may benefit from the recording of multiple successive images. This can include techniques common to several types of microscopy such as frame averaging to improve signal-to-noise ratios (SNR) or time series to study dynamic processes or more specific applications. In the scanning transmission electron microscope, this might include focal series for optical sectioning or aberration measurement, beam damage studies or camera-length series to study the effects of strain; whilst in the scanning tunnelling microscope, this might include bias-voltage series to probe local electronic structure. Whatever the application, such investigations must begin with the careful alignment of these data stacks, an operation that is not always trivial. In addition, the presence of low-frequency scanning distortions can introduce intra-image shifts to the data. Here, we describe an improved automated method of performing non-rigid registration customised for the challenges unique to scanned microscope data specifically addressing the issues of low-SNR data, images containing a large proportion of crystalline material and/or local features of interest such as dislocations or edges. Careful attention has been paid to artefact testing of the non-rigid registration method used, and the importance of this registration for the quantitative interpretation of feature intensities and positions is evaluated. |
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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 |
000218507000008 |
Publication Date |
2015-07-09 |
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 |
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Edition |
|
ISSN |
2198-0926; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
131 |
Open Access |
|
Notes |
312483 Esteem2; esteem2_jra2 |
Approved |
Most recent IF: NA |
Call Number |
c:irua:126944 c:irua:126944 |
Serial |
3043 |
Permanent link to this record |
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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 ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
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 |
|
Series Issue |
|
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 |
Pennycook, T.J.; Martinez, G.T.; Nellist, P.D.; Meyer, J.C. |
Title |
High dose efficiency atomic resolution imaging via electron ptychography |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2019 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
196 |
Issue |
196 |
Pages |
131-135 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Radiation damage places a fundamental limitation on the ability of microscopy to resolve many types of materials at high resolution. Here we evaluate the dose efficiency of phase contrast imaging with electron ptychography. The method is found to be far more resilient to temporal incoherence than conventional and spherical aberration optimized phase contrast imaging, resulting in significantly greater clarity at a given dose. This robustness is explained by the presence of achromatic lines in the four dimensional ptychographic dataset. |
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 |
000451180800018 |
Publication Date |
2018-10-18 |
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 |
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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 |
1 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: 2.843 |
Call Number |
UA @ admin @ c:irua:165939 |
Serial |
6301 |
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 ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
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 |
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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 |
Pennycook, T.J.; Martinez, G.T.; O'Leary, C.M.; Yang, H.; Nellist, P.D. |
Title |
Efficient Phase Contrast Imaging via Electron Ptychography, a Tutorial |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2019 |
Publication |
Microscopy and microanalysis |
Abbreviated Journal |
Microsc Microanal |
Volume |
25 |
Issue |
S2 |
Pages |
2684-2685 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
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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 |
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Publication Date |
2019-08-06 |
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 |
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Edition |
|
ISSN |
1431-9276 |
ISBN |
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Additional Links |
UA library record |
Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
Call Number |
EMAT @ emat @c:irua:172444 |
Serial |
6424 |
Permanent link to this record |
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Author |
Wang, H.S.; Chen, L.; Elibol, K.; He, L.; Wang, H.; Chen, C.; Jiang, C.; Li, C.; Wu, T.; Cong, C.X.; Pennycook, T.J.; Argentero, G.; Zhang, D.; Watanabe, K.; Taniguchi, T.; Wei, W.; Yuan, Q.; Meyer, J.C.; Xie, X. |
Title |
Towards chirality control of graphene nanoribbons embedded in hexagonal boron nitride |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2020 |
Publication |
Nature Materials |
Abbreviated Journal |
Nat Mater |
Volume |
|
Issue |
|
Pages |
1-10 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Oriented trenches are created in h-BN using different catalysts, and used as templates to grow seamlessly integrated armchair and zigzag graphene nanoribbons with chirality-dependent electrical and magnetic conductance properties. The integrated in-plane growth of graphene nanoribbons (GNRs) and hexagonal boron nitride (h-BN) could provide a promising route to achieve integrated circuitry of atomic thickness. However, fabrication of edge-specific GNRs in the lattice of h-BN still remains a significant challenge. Here we developed a two-step growth method and successfully achieved sub-5-nm-wide zigzag and armchair GNRs embedded in h-BN. Further transport measurements reveal that the sub-7-nm-wide zigzag GNRs exhibit openings of the bandgap inversely proportional to their width, while narrow armchair GNRs exhibit some fluctuation in the bandgap-width relationship. An obvious conductance peak is observed in the transfer curves of 8- to 10-nm-wide zigzag GNRs, while it is absent in most armchair GNRs. Zigzag GNRs exhibit a small magnetic conductance, while armchair GNRs have much higher magnetic conductance values. This integrated lateral growth of edge-specific GNRs in h-BN provides a promising route to achieve intricate nanoscale circuits. |
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 |
000571692500001 |
Publication Date |
2020-09-21 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
|
ISSN |
1476-1122; 1476-4660 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
41.2 |
Times cited |
3 |
Open Access |
Not_Open_Access |
Notes |
; H.W. and X.X. thank J.H. Edgar (Kansas State University, USA) for supplying the partial h-BN crystals. H. S. Wang, L. Chen and H. Wang thank M. Liu, X. Qiu and J. Pan from NCNT of China, F. Liou, H. Tsai, M. Crommie from UCB, USA, J. Xue and P. Yu from ShanghaiTech University and S. Wang from SJTU for nc-AFM measurement. H. S. Wang, L. Chen and H. Wang thank B. Sun and S. Li from Hunan University for the fusion of the STEM image and the electron energy loss spectroscopy mapping images. Funding: The work was partially supported by the National Key R&D program (Grant No. 2017YFF0206106), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB30000000), the National Science Foundation of China (Grant No. 51772317, 51302096, 61774040, 91964102), the Science and Technology Commission of Shanghai Municipality (Grant No. 16ZR1442700, 16ZR1402500 18511110700), Shanghai Rising-Star Program (A type) (Grant No.18QA1404800), the Hubei Provincial Natural Science Foundation of China (Grant No. ZRMS2017000370), China Postdoctoral Science Foundation (Grant No. 2017M621563, 2018T110415), and the Fundamental Research Funds of Wuhan City (No. 2016060101010075). C.L. acknowledges support from the European Union's Horizon 2020 research and innovation programme under the Marie Skodowska-Curie grants No. 656378 – Interfacial Reactions. T.J.P. acknowledges funding from European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie grant agreement no. 655760-DIGIPHASE. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and the CREST (JPMJCR15F3), JST. C.X.C. acknowledges financial support from the National Young 1000 Talent Plan of China and the National Key R&D Program of China (No. 2018YFA0703700). L.H. acknowledges financial support from the programme of China Scholarships Council (No. 201706160037). ; |
Approved |
Most recent IF: 41.2; 2020 IF: 39.737 |
Call Number |
UA @ admin @ c:irua:171944 |
Serial |
6633 |
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 ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
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 |
|
Series Issue |
|
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 |
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Author |
Madsen, J.; Pennycook, T.J.; Susi, T. |
Title |
ab initio description of bonding for transmission electron microscopy |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
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 |
|
Series Issue |
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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 |
Mahadi, A.H.; Ye, L.; Fairclough, S.M.; Qu, J.; Wu, S.; Chen, W.; Papaioannou, E.; Ray, B.; Pennycook, T.J.; Haigh, S.J.; Young, N.P.; Tedsree, K.; Metcalfe, I.S.; Tsang, S.C.E. |
Title |
Beyond surface redox and oxygen mobility at pd-polar ceria (100) interface : underlying principle for strong metal-support interactions in green catalysis |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2020 |
Publication |
Applied Catalysis B-Environmental |
Abbreviated Journal |
Appl Catal B-Environ |
Volume |
270 |
Issue |
|
Pages |
118843 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
When ceria is used as a support for many redox catalysis involved in green catalysis, it is well-known that the overlying noble metal can gain access to a significant quantity of oxygen atoms with high mobility and fast reduction and oxidation properties under mild conditions. However, it is as yet unclear what the underlying principle and the nature of the ceria surface involved are. By using two tailored morphologies of ceria nanocrystals, namely cubes and rods, it is demonstrated from Scanning Transmission Electron Microscopy with Electron Energy Loss Spectroscopy (STEM-EELS) mapping and Pulse Isotopic Exchange (PIE) that ceria nano-cubes terminated with a polar surface (100) can give access to more than the top most layer of surface oxygen atoms. Also, they give higher oxygen mobility than ceria nanorods with a non-polar facet of (110). A new insight for the possible additional role of polar ceria surface plays in the oxygen mobility is obtained from Density Functional Theory (DFT) calculations which suggest that the (100) surface sites that has more than half-filled O on same plane can drive oxygen atoms to oxidise adsorbate(s) on Pd due to the strong electrostatic repulsion. |
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 |
000526110500007 |
Publication Date |
2020-03-04 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0926-3373 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
22.1 |
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: 22.1; 2020 IF: 9.446 |
Call Number |
UA @ admin @ c:irua:183959 |
Serial |
6856 |
Permanent link to this record |
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Author |
Hofer, C.; Pennycook, T.J. |
Title |
Reliable phase quantification in focused probe electron ptychography of thin materials |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal Article |
Year |
2023 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
254 |
Issue |
|
Pages |
113829 |
Keywords |
A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; |
Abstract |
Electron ptychography provides highly sensitive, dose efficient phase images which can be corrected for aberrations after the data has been acquired. This is crucial when very precise quantification is required, such as with sensitivity to charge transfer due to bonding. Drift can now be essentially eliminated as a major impediment to focused probe ptychography, which benefits from the availability of easily interpretable simultaneous Z-contrast imaging. However challenges have remained when quantifying the ptychographic phases of atomic sites. The phase response of a single atom has a negative halo which can cause atoms to reduce in phase when brought closer together. When unaccounted for, as in integrating methods of quantification, this effect can completely obscure the effects of charge transfer. Here we provide a new method of quantification that overcomes this challenge, at least for 2D materials, and is robust to experimental parameters such as noise, sample tilt. |
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 |
001071608700001 |
Publication Date |
2023-08-18 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0304-3991 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.2 |
Times cited |
|
Open Access |
|
Notes |
FWO, G013122N ; Horizon 2020 Framework Programme; Horizon 2020; European Research Council, 802123-HDEM ; European Research Council; |
Approved |
Most recent IF: 2.2; 2023 IF: 2.843 |
Call Number |
EMAT @ emat @c:irua:200272 |
Serial |
8987 |
Permanent link to this record |
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Author |
Ning, S.; Xu, W.; Ma, Y.; Loh, L.; Pennycook, T.J.; Zhou, W.; Zhang, F.; Bosman, M.; Pennycook, S.J.; He, Q.; Loh, N.D. |
Title |
Accurate and Robust Calibration of the Uniform Affine Transformation Between Scan-Camera Coordinates for Atom-Resolved In-Focus 4D-STEM Datasets |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2022 |
Publication |
Microscopy and microanalysis |
Abbreviated Journal |
Microsc Microanal |
Volume |
|
Issue |
|
Pages |
1-11 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Accurate geometrical calibration between the scan coordinates and the camera coordinates is critical in four-dimensional scanning transmission electron microscopy (4D-STEM) for both quantitative imaging and ptychographic reconstructions. For atomic-resolved, in-focus 4D-STEM datasets, we propose a hybrid method incorporating two sub-routines, namely a J-matrix method and a Fourier method, which can calibrate the uniform affine transformation between the scan-camera coordinates using raw data, without a priori knowledge about the crystal structure of the specimen. The hybrid method is found robust against scan distortions and residual probe aberrations. It is also effective even when defects are present in the specimen, or the specimen becomes relatively thick. We will demonstrate that a successful geometrical calibration with the hybrid method will lead to a more reliable recovery of both the specimen and the electron probe in a ptychographic reconstruction. We will also show that, although the elimination of local scan position errors still requires an iterative approach, the rate of convergence can be improved, and the residual errors can be further reduced if the hybrid method can be firstly applied for initial calibration. The code is made available as a simple-to-use tool to correct affine transformations of the scan-camera coordinates in 4D-STEM experiments. |
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 |
000767045700001 |
Publication Date |
2022-03-09 |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1431-9276 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.8 |
Times cited |
|
Open Access |
OpenAccess |
Notes |
N. D. Loh kindly acknowledges support from NUS Early Career Research Award (R-154-000-B35-133), MOE’s AcRF Tier 1 grant nr. R-284-000-172-114 and NRF CRP grant number NRF-CRP16-2015-05. Q. He would also like to acknowledge the support of the National Research Foundation (NRF) Singapore, under its NRF Fellowship (NRF-NRFF11-2019-0002). W. Zhou acknowledges the support from Beijing Outstanding Young Scientist Program (BJJWZYJH01201914430039). F. Zhang acknowledges the support of the National Natural Science Foundation of China (11775105, 12074167). T. J. Pennycook acknowledges funding under the European Union’s Horizon 2020 research and innovation programme from the European Research Council (ERC) Grant agreement No. 802123-HDEM. |
Approved |
Most recent IF: 2.8 |
Call Number |
EMAT @ emat @c:irua:186958 |
Serial |
6957 |
Permanent link to this record |
|
|
|
Author |
Hofer, C.; Gao, C.; Chennit, T.; Yuan, B.; Pennycook, T.J. |
Title |
Phase offset method of ptychographic contrast reversal correction |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2024 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
|
Issue |
|
Pages |
113922 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
|
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 |
|
Language |
|
Wos |
001164447000001 |
Publication Date |
2024-01-08 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0304-3991 |
ISBN |
|
Additional Links |
UA library record; WoS full record |
Impact Factor |
2.2 |
Times cited |
|
Open Access |
Not_Open_Access |
Notes |
FWO, G013122N ; Horizon 2020 Framework Programme; European Research Council, 802123-HDEM ; European Research Council; |
Approved |
Most recent IF: 2.2; 2024 IF: 2.843 |
Call Number |
EMAT @ emat @c:irua:202379 |
Serial |
8988 |
Permanent link to this record |
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|
|
Author |
Gao, C.; Hofer, C.; Jannis, D.; Béché, A.; Verbeeck, J.; Pennycook, T.J. |
Title |
Overcoming contrast reversals in focused probe ptychography of thick materials: An optimal pipeline for efficiently determining local atomic structure in materials science |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2022 |
Publication |
Applied physics letters |
Abbreviated Journal |
Appl Phys Lett |
Volume |
121 |
Issue |
8 |
Pages |
081906 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Ptychography provides highly efficient imaging in scanning transmission electron microscopy (STEM), but questions have remained over its applicability to strongly scattering samples such as those most commonly seen in materials science. Although contrast reversals can appear in ptychographic phase images as the projected potentials of the sample increase, we show here how these can be easily overcome by a small amount of defocus. The amount of defocus is small enough that it not only can exist naturally when focusing using the annular dark field (ADF) signal but can also be adjusted post acquisition. The ptychographic images of strongly scattering materials are clearer at finite doses than other STEM techniques and can better reveal light atomic columns within heavy lattices. In addition, data for ptychography can now be collected simultaneously with the fastest of ADF scans. This combination of sensitivity and interpretability presents an ideal workflow for materials science. |
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 |
|
Wos |
000844403300006 |
Publication Date |
2022-08-22 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0003-6951 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
4 |
Times cited |
9 |
Open Access |
OpenAccess |
Notes |
European Research Council, 802123-HDEM ; HORIZON EUROPE European Research Council, 823717-ESTEEM3 ; Fonds Wetenschappelijk Onderzoek, G042920N ; Fonds Wetenschappelijk Onderzoek, G042820N ; Horizon 2020 Framework Programme, 101017720 ; Fonds Wetenschappelijk Onderzoek, G013122N ; esteem3reported; esteem3jra |
Approved |
Most recent IF: 4 |
Call Number |
EMAT @ emat @c:irua:190670 |
Serial |
7120 |
Permanent link to this record |
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|
|
Author |
Bian, G.; Ageeva, O.; Roddatis, V.; Li, C.; Pennycook, T.J.; Habler, G.; Abart, R. |
Title |
Crystal structure controls on oriented primary magnetite micro-inclusions in plagioclase From oceanic gabbro |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2023 |
Publication |
Journal of petrology |
Abbreviated Journal |
|
Volume |
64 |
Issue |
3 |
Pages |
egad008-18 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Oriented needle-, lath- and plate-shaped magnetite micro-inclusions in rock forming plagioclase from mafic intrusive rocks, were investigated using correlated optical microscopy and scanning transmission electron microscopy. The magnetite micro-inclusions were analysed on cuts parallel and perpendicular to the inclusion-elongation directions. The crystal structures of the two phases are in direct contact along the interfaces. The shape, shape orientation and crystallographic orientation relationships between the magnetite micro-inclusions and the plagioclase host appear to be controlled by the tendency of the system to optimise lattice match along the interfaces. The elongation direction of the inclusions ensures good match between prominent oxygen layers in the magnetite and plagioclase crystal structures across the interfaces bounding the inclusions parallel to their elongation direction. In cross-section, additional modes of lattice match, such as the commensurate impingement of magnetite and plagioclase lattice planes along the interfaces, the parallel alignment of the interfaces to low-index lattice planes of magnetite or plagioclase, or the parallel alignment to low index lattice planes of both phases are observed, which appear to control the selection of interface facets, as well as the shape and crystallographic orientation relationships between magnetite micro-inclusions and plagioclase host. The systematics of the inclusion cross-sectional shapes and crystallographic orientation relationships indicate recrystallisation of magnetite with potential implications for natural remanent magnetisation of magnetite-bearing plagioclase grains. |
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 |
001010636400007 |
Publication Date |
2023-01-28 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0022-3530 |
ISBN |
|
Additional Links |
UA library record; WoS full record |
Impact Factor |
3.9 |
Times cited |
|
Open Access |
OpenAccess |
Notes |
|
Approved |
Most recent IF: 3.9; 2023 IF: 3.28 |
Call Number |
UA @ admin @ c:irua:195160 |
Serial |
7292 |
Permanent link to this record |
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|
|
Author |
Soltan, S.; Macke, S.; Ilse, S.E.; Pennycook, T.; Zhang, Z.L.; Christiani, G.; Benckiser, E.; Schuetz, G.; Goering, E. |
Title |
Ferromagnetic order controlled by the magnetic interface of LaNiO3/La2/3Ca1/3MnO3 superlattices |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2023 |
Publication |
Scientific reports |
Abbreviated Journal |
|
Volume |
13 |
Issue |
1 |
Pages |
1-9 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
Interface engineering in complex oxide superlattices is a growing field, enabling manipulation of the exceptional properties of these materials, and also providing access to new phases and emergent physical phenomena. Here we demonstrate how interfacial interactions can induce a complex charge and spin structure in a bulk paramagnetic material. We investigate a superlattice (SLs) consisting of paramagnetic LaNiO3 (LNO) and highly spin-polarized ferromagnetic La2/3Ca1/3MnO3 (LCMO), grown on SrTiO3 (001) substrate. We observed emerging magnetism in LNO through an exchange bias mechanism at the interfaces in X-ray resonant magnetic reflectivity. We find non-symmetric interface induced magnetization profiles in LNO and LCMO which we relate to a periodic complex charge and spin superstructure. High resolution scanning transmission electron microscopy images reveal that the upper and lower interfaces exhibit no significant structural variations. The different long range magnetic order emerging in LNO layers demonstrates the enormous potential of interfacial reconstruction as a tool for tailored electronic properties. |
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 |
|
Wos |
000985158100013 |
Publication Date |
2023-03-26 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
2045-2322 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
4.6 |
Times cited |
|
Open Access |
OpenAccess |
Notes |
|
Approved |
Most recent IF: 4.6; 2023 IF: 4.259 |
Call Number |
UA @ admin @ c:irua:197426 |
Serial |
8867 |
Permanent link to this record |
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|
|
Author |
Hofer, C.; Mustonen, K.; Skakalova, V.; Pennycook, T.J. |
Title |
Picometer-precision few-tilt ptychotomography of 2D materials |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2023 |
Publication |
2D materials |
Abbreviated Journal |
|
Volume |
10 |
Issue |
3 |
Pages |
035029-7 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
From ripples to defects, edges and grain boundaries, the 3D atomic structure of 2D materials is critical to their properties. However the damage inflicted by conventional 3D analysis precludes its use with fragile 2D materials, particularly for the analysis of local defects. Here we dramatically increase the potential for precise local 3D atomic structure analysis of 2D materials, with both greatly improved dose efficiency and sensitivity to light elements. We demonstrate light atoms can now be located in complex 2D materials with picometer precision at doses 30 times lower than previously possible. Moreover we demonstrate this using WS2, in which the light atoms are practically invisible to conventional methods at low doses. The key advance is combining the concept of few tilt tomography with highly dose efficient ptychography in scanning transmission electron microscopy. We further demonstrate the method experimentally with the even more challenging and newly discovered 2D CuI, leveraging a new extremely high temporal resolution camera. |
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 |
001013151600001 |
Publication Date |
2023-06-12 |
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 |
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Edition |
|
ISSN |
2053-1583 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
5.5 |
Times cited |
|
Open Access |
OpenAccess |
Notes |
|
Approved |
Most recent IF: 5.5; 2023 IF: 6.937 |
Call Number |
UA @ admin @ c:irua:197809 |
Serial |
8915 |
Permanent link to this record |
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|
|
Author |
Gao, C.; Hofer, C.; Pennycook, T.J. |
Title |
On central focusing for contrast optimization in direct electron ptychography of thick samples |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2024 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
|
Volume |
256 |
Issue |
|
Pages |
113879-7 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Ptychography provides high dose efficiency images that can reveal light elements next to heavy atoms. However, despite ptychography having an otherwise single signed contrast transfer function, contrast reversals can occur when the projected potential becomes strong for both direct and iterative inversion ptychography methods. It has recently been shown that these reversals can often be counteracted in direct ptychography methods by adapting the focus. Here we provide an explanation of why the best contrast is often found with the probe focused to the middle of the sample. The phase contribution due to defocus at each sample slice above and below the central plane in this configuration effectively cancels out, which can prevent contrast reversals when dynamical scattering effects are not overly strong. In addition we show that the convergence angle can be an important consideration for removal of contrast reversals in relatively thin samples. |
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 |
001112166400001 |
Publication Date |
2023-11-03 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0304-3991 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.2 |
Times cited |
|
Open Access |
Not_Open_Access |
Notes |
|
Approved |
Most recent IF: 2.2; 2024 IF: 2.843 |
Call Number |
UA @ admin @ c:irua:202029 |
Serial |
9066 |
Permanent link to this record |
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|
|
Author |
Singh, A.; Yuan, B.; Rahman, M.H.; Yang, H.; De, A.; Park, J.Y.; Zhang, S.; Huang, L.; Mannodi-Kanakkithodi, A.; Pennycook, T.J.; Dou, L. |
Title |
Two-dimensional halide Pb-perovskite-double perovskite epitaxial heterostructures |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
A1 Journal article |
Year |
2023 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
|
Volume |
145 |
Issue |
36 |
Pages |
19885-19893 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Epitaxial heterostructures of two-dimensional (2D) halide perovskites offer a new platform for studying intriguing structural, optical, and electronic properties. However, difficulties with the stability of Pb- and Sn-based heterostructures have repeatedly slowed the progress. Recently, Pb-free halide double perovskites are gaining a lot of attention due to their superior stability and greater chemical diversity, but they have not been successfully incorporated into epitaxial heterostructures for further investigation. Here, we report epitaxial core-shell heterostructures via growing Pb-free double perovskites (involving combinations of Ag(I)-Bi(III), Ag-Sb, Ag-In, Na-Bi, Na-Sb, and Na-In) around Pb perovskite 2D crystals. Distinct from Pb-Pb and Pb-Sn perovskite heterostructures, growths of the Pb-free shell at 45 degrees on the (100) surface of the lead perovskite core are observed in all Pb-free cases. The in-depth structural analysis carried out with electron diffraction unequivocally demonstrates the growth of the Pb-free shell along the [110] direction of the Pb perovskite, which is likely due to the relatively lower surface energy of the (110) surface. Furthermore, an investigation of anionic interdiffusion across heterostructure interfaces under the influence of heat was carried out. Interestingly, halide anion diffusion in the Pb-free 2D perovskites is found to be significantly suppressed as compared to Pb-based 2D perovskites. The great structural tunability and excellent stability of Pb-free perovskite heterostructures may find uses in electronic and optoelectronic devices in the near future. |
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 |
001060980300001 |
Publication Date |
2023-08-31 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0002-7863 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
15 |
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: 15; 2023 IF: 13.858 |
Call Number |
UA @ admin @ c:irua:200342 |
Serial |
9111 |
Permanent link to this record |
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|
|
Author |
Friedrich, T.; Yu, C.-P.; Verbeek, J.; Pennycook, T.; Van Aert, S. |
Title |
Phase retrieval from 4-dimensional electron diffraction datasets |
Type ![sorted by Type field, ascending order (up)](img/sort_asc.gif) |
P1 Proceeding |
Year |
2021 |
Publication |
Proceedings
T2 – IEEE International Conference on Image Processing (ICIP), SEP 19-22, 2021, Electr. network |
Abbreviated Journal |
|
Volume |
|
Issue |
|
Pages |
3453-3457 |
Keywords |
P1 Proceeding; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
We present a computational imaging mode for large scale electron microscopy data, which retrieves a complex wave from noisy/sparse intensity recordings using a deep learning approach and subsequently reconstructs an image of the specimen from the Convolutional Neural Network (CNN) predicted exit waves. We demonstrate that an appropriate forward model in combination with open data frameworks can be used to generate large synthetic datasets for training. In combination with augmenting the data with Poisson noise corresponding to varying dose-values, we effectively eliminate overfitting issues. The U-NET[1] based architecture of the CNN is adapted to the task at hand and performs well while maintaining a relatively small size and fast performance. The validity of the approach is confirmed by comparing the reconstruction to well-established methods using simulated, as well as real electron microscopy data. The proposed method is shown to be effective particularly in the low dose range, evident by strong suppression of noise, good spatial resolution, and sensitivity to different atom types, enabling the simultaneous visualisation of light and heavy elements and making different atomic species distinguishable. Since the method acts on a very local scale and is comparatively fast it bears the potential to be used for near-real-time reconstruction during data acquisition. |
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 |
|
Wos |
000819455103114 |
Publication Date |
2021-08-23 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
978-1-6654-4115-5 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
|
Open Access |
OpenAccess |
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ admin @ c:irua:189462 |
Serial |
7089 |
Permanent link to this record |