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Author |
Robert, Hl.; Lobato, I.; Lyu, Fj.; Chen, Q.; Van Aert, S.; Van Dyck, D.; Müller-Caspary, K. |
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Title |
Dynamical diffraction of high-energy electrons investigated by focal series momentum-resolved scanning transmission electron microscopy at atomic resolution |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
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Volume |
233 |
Issue |
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Pages |
113425 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab |
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Abstract  |
We report a study of scattering dynamics in crystals employing momentum-resolved scanning transmission
electron microscopy under varying illumination conditions. As we perform successive changes of the probe
focus, multiple real-space signals are obtained in dependence of the shape of the incident electron wave.
With support from extensive simulations, each signal is shown to be characterised by an optimum focus for
which the contrast is maximum and which differs among different signals. For instance, a systematic focus
mismatch is found between images formed by high-angle scattering, being sensitive to thickness and chemical
composition, and the first moment in diffraction space, being sensitive to electric fields. It follows that a single
recording at one specific probe focus is usually insufficient to characterise materials comprehensively. Most
importantly, we demonstrate in experiment and simulation that the second moment ( |
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Wos |
000734396800009 |
Publication Date |
2021-11-13 |
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ISSN |
0304-3991 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.2 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
We thank Dr. Florian Winkler for valuable discussions and experimental work at the early stages of this study. This work was supported by the Initiative and Network Fund of the Helmholtz Association (Germany) under contracts VH-NG-1317 and ZT-I-0025. This project furthermore received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 770887). |
Approved |
Most recent IF: 2.2 |
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Call Number |
EMAT @ emat @c:irua:184833 |
Serial |
6898 |
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Author |
Toso, S.; Akkerman, Q.A.; Martin-Garcia, B.; Prato, M.; Zito, J.; Infante, I.; Dang, Z.; Moliterni, A.; Giannini, C.; Bladt, E.; Lobato, I.; Ramade, J.; Bals, S.; Buha, J.; Spirito, D.; Mugnaioli, E.; Gemmi, M.; Manna, L. |
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Title |
Nanocrystals of lead chalcohalides : a series of kinetically trapped metastable nanostructures |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Journal Of The American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
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Volume |
142 |
Issue |
22 |
Pages |
10198-10211 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We report the colloidal synthesis of a series of surfactant-stabilized lead chalcohalide nanocrystals. Our work is mainly focused on Pb4S3Br2, a chalcohalide phase unknown to date that does not belong to the ambient-pressure PbS-PbBr2 phase diagram. The Pb4S3Br2 nanocrystals herein feature a remarkably narrow size distribution (with a size dispersion as low as 5%), a good size tunability (from 7 to similar to 30 nm), an indirect bandgap, photoconductivity (responsivity = 4 +/- 1 mA/W), and stability for months in air. A crystal structure is proposed for this new material by combining the information from 3D electron diffraction and electron tomography of a single nanocrystal, X-ray powder diffraction, and density functional theory calculations. Such a structure is closely related to that of the recently discovered high-pressure chalcohalide Pb4S3I2 phase, and indeed we were able to extend our synthesis scheme to Pb4S3I2 colloidal nanocrystals, whose structure matches the one that has been published for the bulk. Finally, we could also prepare nanocrystals of Pb3S2Cl2, which proved to be a structural analogue of the recently reported bulk Pb3Se2Br2 phase. It is remarkable that one high-pressure structure (for Pb4S3I2) and two metastable structures that had not yet been reported (for Pb4S3Br2 and Pb3S2Cl2) can be prepared on the nanoscale by wet-chemical approaches. This highlights the important role of colloidal chemistry in the discovery of new materials and motivates further exploration into metal chalcohalide nanocrystals. |
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Wos |
000538526500035 |
Publication Date |
2020-05-06 |
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ISSN |
0002-7863 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
15 |
Times cited |
32 |
Open Access |
OpenAccess |
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Notes |
; We would like to thank Dr. A. Toma for the access to the IIT clean room facilities' SEM/FIB and evaporators, the Smart Materials group (IIT) for the access to the ATR-FTIR equipment, S. Marras for the support during XRPD measurements, G. Pugliese for help with the TGA measurements, M. Campolucci for help with the experiments on NC growth kinetics, S. Lauciello for help with the SEM-EDX analyses, and D. Baranov and R. Brescia for the helpful discussions. We also acknowledge funding from the Programme for Research and Innovation Horizon 2020 (2014-2020) under the Marie Sklodowska-Curie Grant Agreement COMPASS No. 691185. I.I. acknowledges the Dutch NWO for financial support under the Vidi scheme (Grant No. 723.013.002). S.B. acknowledges support by means of the ERC Consolidator Grant No. 815128 REALNANO. E. M. and M.G acknowledge the Regione Toscana for funding the purchase of the Timepix detector through the FELIX project (Por CREO FESR 2014-2020 action). ; sygma |
Approved |
Most recent IF: 15; 2020 IF: 13.858 |
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Call Number |
UA @ admin @ c:irua:170218 |
Serial |
6566 |
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