by Merijn Pen | Jul 10, 2017
Dr. Qiang Xu
Kavli Institute of Nanoscience, Delft University of Technology,The Netherlands Authors | Qiang Xu, Meng-Yue Wu, Grégory F. Schneider, Lothar Houben, Sairam K. Malladi, Cees Dekker, Emrah Yucelen, Rafal E. Dunin-Borkowski and Henny W. Zandbergen. Email | h.w.zandbergen@tudelft.nl
| Application |
Controllable Atomic Scale Patterning of Freestanding Monolayer Graphene at Elevated Temperature |
| Authors |
Qiang Xu, Meng-Yue Wu, Grégory F. Schneider, Lothar Houben, Sairam K. Malladi, Cees Dekker, Emrah Yucelen, Rafal E. Dunin-Borkowski and Henny W. Zandbergen. |
| Journal |
ACS Nano, 2013, 7 (2), pp 1566–1572 |
| Sample |
Graphene |
| Topic |
Contamination Free, 2D Materials, Soft Matter, E-Beam Sensitive Imaging |
| Field |
Material Science, Chemistry, Electronics, Life Science |
| Techniques |
HRTEM, HRSTEM, EELS, Diffraction |
| Keywords |
Graphene; Controlled Sculpting; Nondestructive Imaging; Nanopatterning; Self-repair |
| Publication / D.O.I. |
Full Publication Here – DOI: 10.1021/nn3053582 |
Controllable Atomic Scale Patterning of Freestanding Monolayer Graphene at Elevated Temperature
ABSTRACT: In order to harvest the many promising properties of graphene in (electronic) applications, a technique is required to cut, shape, or sculpt the material on the nanoscale without inducing damage to its atomic structure, as this drastically influences the electronic properties of the nanostructure. Here, we reveal a temperature-dependent self-repair mechanism that allows near-damage-free atomic-scale sculpting of graphene using a focused electron beam. We demonstrate that by sculpting at temperatures above 600 C, an intrinsic self-repair mechanism keeps the graphene in a single-crystalline state during cutting, even though the electron beam induces considerable damage. Self-repair is mediated by mobile carbon ad-atoms that constantly repair the defects caused by the electron beam. Our technique allows reproducible fabrication and simultaneous imaging of single-crystalline free-standing nanoribbons, nanotubes, nanopores, and single carbon chains.
FIGURE ABOVE: Annular dark field STEM images of graphene ribbon arrays sculpted in a reproducible way by using a script-controlled electron beam at elevated temperature. After the first sculpting process, the patterns were imaged as shown in (a). Next, each ribbon was reduced in width precisely, and image (b) was acquired. Intensity line profiles across the ribbon outlined by the white frames in (a) and (b) are shown in (c) and (d), respectively. The width of the ribbon is estimated to be 4.0 nm after initial sculpting and 1.9 nm after final sculpting.
DENSsolutions Comments
Objective & Goal
Graphene, carbon nanotube and other soft-mater materials suffers irradiation damage caused by high energy electron beam during TEM characterization. The e-beam damage limits the observation time or observation electron beam condition, thus requiring a way to prevent. Moreover, application of graphene needs to patterning graphene into various functional devices with nano-size geometry. The e-beam induced damage can be utilized for creating a lithography method for graphene patterning. Achieving control of e-beam damage of graphene becomes an essential topic.
Benefit
DENSsolutions heating system provides the extreme high stability of sample at elevated temperature (sample spatial drift less than 0.5nm/min) At the elevated temperature, the e-beam induced defects of the sample can be repaired with a corresponding speed, therefore, provides an extra parameter for control of e-beam damage.
by Merijn Pen | Jul 10, 2017
Dr. Marijn A. van Huis
Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands.
Authors | Marijn A. van Huis, Lucas T. Kunneman, Karin Overgaag, Qiang Xu, Gregory Pandraud, Henny W. Zandbergen and Daniël Vanmaekelbergh. Email | M.A.vanHuis@uu.nl
| Application |
Low-Temperature Nanocrystal Unification through Rotations and Relaxations Probed by In-situ Transmission Electron Microscopy |
| Authors |
Marijn A. van Huis, Lucas T. Kunneman, Karin Overgaag, Qiang Xu, Gregory Pandraud, Henny W. Zandbergen and Daniël Vanmaekelbergh. |
| Journal |
Nano Lett., 2008, 8 (11), pp 3959–3963 (cited 79 times) |
| Sample |
Nanoparticles |
| Topic |
Self assembly, Sintering, Stability of Catalyst |
| Techniques |
Materials Science, Chemistry, Electronics |
| Publication |
Full publication here DOI: 10.1021/nl8024467e |
Low-Temperature Nanocrystal Unification through Rotations and Relaxations Probed by In-situ Transmission Electron Microscopy
ABSTRACT: Through the mechanism of “oriented attachment”, small nanocrystals can fuse into a wide variety of one- and two-dimensional nanostructures. This fusion phenomenon is investigated in detail by low-temperature annealing of a two-dimensional array of 10 nm-sized PbSe nanocrystals, in situ in the transmission electron microscope. The researchers have revealed a complex chain of processes; after coalescence, the connected nanocrystals undergo consecutive rotations in three-dimensional space, followed by drastic interfacial relaxations whereby full fusion is obtained.
FIGURE RIGHT: Schematic representation of the entire fusion process indicated by experimental data: (i) attachment due to surfactant evaporation, (ii) rotations to a planar alignment, (iii) subsequent rotation to a nearly full 3D alignment, and (iv) relaxations resulting in removal of the defective interface in order to achieve complete fusion.
FIGURE LEFT: Stills of in situ TEM recordings, showing the evolution PbSe quantum dots (QDs) during three fusion events. The scale bars indicate 4 nm. In general, one QD is centered in the field of view because it is not known beforehand with which other QD it will fuse. (a-h) First event, two 10 nm PbSe QDs fuse into a single crystal at a temperature of 120 °C. Panels a-d: Rotation over 6° in the plane of view, establishing alignment of the (111) planes in panels d and e. Panels e-h: Subsequent rotation of the central nanocluster perpendicular to the field of view. A third QD attaches at the bottom in image h. (i-m) Second event, two 10 nm QDs with hexylamine capping fusing at a temperature of 120 °C. Panels k and l: A rotation of 7° removes the misalignment between the (022) planes, 3D alignment is obtained in panel m where the fused crystal is projected along (011). (n-w) Multisized PbSe QDs fusing into a nanorod. Panels n-u: The small nanocluster no. 3 rotates to align with the larger dot at its left. Movie 3 in the Supporting Information shows that the rotation is not smooth, but irregular as a function of time. Panel v: Four dots have fused into a 4 dot single crystal. The small dot that rotated has been assimilated into the rod. Panel w: The rod has rotated around its own axis, changing the projection of the crystal.
DENSsolutions Comments
Orientation attachment is one of self-assembly process, in which the components of a system assemble themselves spontaneously via an interaction to form a larger functional unit. The ability to assemble nanoparticles into well-defined configuration in space is crucial to the development of electronic devices that are small but can contain plenty of information. The spatial arrangements of these self-assembled nanoparticles can be potentially used to build increasingly complex structures leading to a wide variety of materials that can be used for different purposes. Moreover this process is also crucial for understanding of traditional sintering process, which heavily influences the catalysis activity of nanoparticles at elevated temperature.
The DENSsolutions heating system provides accurate temperature environment that enable this dynamic process in a controlled manner such that the whole process can be visualized at atomic level, leading to an intuitive understanding.
by Merijn Pen | Jul 10, 2017
Dr. Amanda S. Barnard
CSIRO Materials Science & Engineering, Australia Authors | Amanda S. Barnard, Neil P. Young, Angus I. Kirkland, Marijn A. van Huis and Huifang Xu. Email | Amanda.Barnard@csiro.au
| Application |
Nanogold – A Qualitative Phase Map (cited 86 times) |
| Authors |
Amanda S. Barnard, Neil P. Young, Angus I. Kirkland, Marijn A. van Huis and Huifang Xu. |
| Journal |
ACS Nano, 2009, 3 (6), pp 1431–1436 |
| Sample |
Nanoparticles |
| Topic |
Catalyst Stability, Phase Transformation |
| Techniques |
HRTEM |
| Keywords |
Gold; Nanoparticles; Shape; Phase diagram; Thermodynamics; Modeling |
| Publication / D.O.I. |
Full publication here DOI: 10.1021/nn900220k |
Nanogold – A Qualitative Phase Map
ABSTRACT: The development of the next generation of nanotechnologies requires precise control of the size, shape, and structure of individual components in a variety of chemical and engineering environments. This includes synthesis, storage, operational environments and, since these products will ultimately be discarded, their interaction with natural ecosystems.
Much of the important information that determines these properties is contained within nanoscale phase diagrams, but quantitative phase maps that include surface effects and critical diameter (along with temperature and pressure) remain elusive. Here we present the first quantitative equilibrium phase map for gold nanoparticles together with experimental verification, based on relativistic ab initio thermodynamics and in situ high-resolution electron microscopy at elevated temperatures.
Figure: “Until recently growing gold nanoparticles was a little like a box of chocolates – you never know what you were going to get!”
DENSsolutions Comments
Nanoparticles of gold are currently attracting considerable attention for use in biomedical applications including drug delivering, heating, sensing and in nanocatalysis. However, our ability to control the properties upon which these applications are based is still intrinsically linked to the nanomorphology of individual particles.
Most theoretical models predict that, in general, the more perfect the nanoparticles, the better they perform. However, real nanoparticles are rarely crystallographically ideal, and planar defects such as contact twins and intrinsic or extrinsic stacking faults, form during growth in materials with low stacking fault or twin boundary energy, and surface energy anisotropy. Gold features in this group, often exhibiting structural and morphological modifications including single or multiple (parallel, contact) twinning and cyclic twinning resulting in decahedral and truncated decahedral structures. Verifying a phase map given by theoretical simulation is very challenging undertaking, which requires mapping gold particles at various elevated temperatures.
The researchers using a range of DENSsolutions heating systems were able to observe gold particles at various elevated temperature. The extreme low drift at elevated temperature allows structural and shape transformations in individual gold particles that could be imaged with atomic resolution. By using approach, the researchers succeed in mapping the gold phase diagram experimentally.
by Merijn Pen | Jul 10, 2017
Dr. Albert Figuerola
Istituto Italiano di Tecnologia, Genova, Italy
Author | Albert Figuerola, Marijn van Huis, Marco Zanella, Alessandro Genovese, Sergio Marras, Andrea Falqui, Henny W. Zandbergen, Roberto Cingolani and Liberato Manna.
Email | liberato.manna@iit.it.
| Application |
Epitaxial CdSe-Au Nanocrystal Heterostructures by Thermal Annealing (Cited by 59 times) |
| Authors |
Albert Figuerola, Marijn van Huis, Marco Zanella, Alessandro Genovese, Sergio Marras, Andrea Falqui, Henny W. Zandbergen, Roberto Cingolani and Liberato Manna. |
| Journal |
Nano Lett., 2010, 10 (8), pp 3028–3036 |
| Sample |
Nano-Particles |
| Topic |
Interface, Diffusion, Catalyst stability |
| Field |
Chemistry, Material Science, Electronics |
| Techniques |
HRTEM |
| Keywords |
Nanorods; nanocrystals; self-assembly; epitaxy; orientation relationship; interface; hybrid nanocrystals; gold; cadmium selenide; annealing |
| Publication |
Full publication here – DOI: 10.1021/nl101482q |
Epitaxial CdSe-Au Nanocrystal Heterostructures by Thermal Annealing
ABSTRACT: The thermal evolution of a collection of heterogeneous CdSe−Au nanosystems (Au-decorated CdSe nanorods, networks, vertical assemblies) prepared by wet-chemical approaches was monitored in situ in the transmission electron microscope. In contrast to interfaces that are formed during kinetically controlled wet chemical synthesis, heating under vacuum conditions results in distinct and well-defined CdSe/Au interfaces, located at the CdSe polar surfaces. The high quality of these interfaces should make the heterostructures more suitable for use in nanoscale electronic devices.
FIGURE LEFT: Enlargement and flattening of the CdSe/Au interface (a-c). During heating at a high heating rate (2 K/s), the width of the interface grew by a factor of 3. Images are shown corresponding to temperatures of 150 °C (a), 250 °C (b), and 300 °C (c), respectively. Such an interface reconstruction enables the two crystal lattices to accommodate to each other to maximize the number of covalent bonds between them. various CdSe/Au interfaces with both the CdSe and the Au crystals in identifiable zone axes are shown (d-f) All configurations show the same epitaxial relationship, as indicated in the figure.
DENSsolutions Comments
Colloidal inorganic nanocrystals of semiconductors are promising materials in a variety of applications. For example, in photocatalysis and photovoltaics, the photoinduced generation of charge carriers in nanocrystals can lead to the oxidation/reduction of molecular species or to the generation of clean electrical energy, respectively. In both cases, the performance of the material depends strongly on its charge separation ability and on the construction of suitable nanocrystal-electrode interfaces.
The growth of metallic domains directly on the surface of the semiconductor nanocrystals can help to improve both factors. Thus the nature of the metal-semiconductor nanointerface and its influence on the local electronic structure of the nanorod have become subjects of particular interest in the past decade. Various efforts are devoted to improve the interface between metal and semiconductors.
Using the DENSsolutions heating system, the researchers are able to observe the In-Situ thermal evolution of heterogeneous CdSe-Au nanosystem. The low drift at elevated temperature allows structural and shape transformations in individual nanocrystals that could be imaged in real time with atomic resolution. The researchers showed that such treatment leads to heterostructures with better defined metal-semiconductor interfaces. The high quality of these interfaces should make the heterostructures more suitable for use in nanoscale electronic devices.
by Merijn Pen | Jul 10, 2017
Dr. Sairam K. Malladi
Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands. Authors | Sairam K. Malladi, Qiang Xu, Marijn A. van Huis, Frans D. Tichelaar, K. Joost Batenburg, Emrah Yücelen, Beata Dubiel, Aleksandra Czyrska-Filemonowicz, and Henny W. Zandbergen. Email | H.W.Zandbergen@tudelft.nl.
| Application |
Real-Time Atomic Scale Imaging of Nanostructural Evolution in Aluminum Alloys |
| Authors |
Sairam K. Malladi, Qiang Xu, Marijn A. van Huis, Frans D. Tichelaar, K. Joost Batenburg, Emrah Yücelen, Beata Dubiel, Aleksandra Czyrska-Filemonowicz, and Henny W. Zandbergen. |
| Journal |
Nano Lett., 2014, 14 (1), pp 384–389 |
| Sample |
FIB lamella, Metal |
| Topic |
Heat Treatment, Aging, Precipitation |
| Field |
Materials Science, Micro Electronics |
| Techniques |
HRTEM, EDX mapping |
| Keywords |
In situ (S)TEM; precipitation; aluminum alloys |
| Publication |
Full Publication Here – DOI 10.1021/nl404565j |
Real-Time Atomic Scale Imaging of Nanostructural Evolution in Aluminum Alloys
ABSTRACT: We present a new approach to study the three dimensional alloys during heat treatments such as commonly used for improving overall material properties. It relies on in situ heating in a high-resolution scanning transmission electron microscope (STEM). The approach is demonstrated using a commercial Al alloy AA2024 at 100−240 °C, showing in unparalleled detail where and how precipitates nucleate, grow, or dissolve. The observed size evolution of individual precipitates enables a separation between nucleation and growth phenomena, necessary for the development of refined growth models. We conclude that the in situ heating STEM approach opens a route to a much faster determination of the interplay between local compositions, heat treatments, microstructure, and mechanical properties of new alloys.
FIGURE ABOVE: STEM imaging and EDX maps obtained at each of the intermediate stages of heat-treatment. These maps are obtained with a frame size of 512×512 pixels2 and a frame time of 100 s, averaged over three frames. Notice the Cu redistribution associated with the precipitation at grain boundaries and precipitation in the matrix during the heat-treatment processes. The lath-like nanoprecipitates are enriched with Cu and Mg, suggesting S-phase-type compositions. Throughout the heat-treatment process, the Mn-rich precipitates remained as they are at room temperature.
DENSsolutions Comments:
Most commercial engineering alloys undergo heat treatments to change their intrinsic microstructural properties, such as elemental distribution and precipitate density, to enhance their extrinsic physical properties such as mechanical strength. Despite the key importance of these treatments, studies of the compositional and structural evolution of alloys undergoing heat treatments are fragmented and time consuming as they have been carried out on a set of different samples taken at intermediate stages, which are postmortem data that do not show the evolution of the same area. Achieving in situ TEM observation of heat treatment process at atomic scale enable a full understanding of the relation among process, structure and properties.
The DENSsolutions heating system provides the minimal specimen drift at elevated temperature, allowing a novel in situ method to investigate the aging hardening process that the structural and compositional evolution of alloys can be directly analyzed with time and temperature down to atomic scale.
