scholarly journals Analysis of complex, beam-sensitive materials by transmission electron microscopy and associated techniques

2020 ◽  
Vol 378 (2186) ◽  
pp. 20190601
Author(s):  
Martha Ilett ◽  
Mark S'ari ◽  
Helen Freeman ◽  
Zabeada Aslam ◽  
Natalia Koniuch ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Molecular Crystals ◽  
Optimum Dose ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Imaging And Spectroscopy ◽  
And Function

We review the use of transmission electron microscopy (TEM) and associated techniques for the analysis of beam-sensitive materials and complex, multiphase systems in-situ or close to their native state. We focus on materials prone to damage by radiolysis and explain that this process cannot be eliminated or switched off, requiring TEM analysis to be done within a dose budget to achieve an optimum dose-limited resolution. We highlight the importance of determining the damage sensitivity of a particular system in terms of characteristic changes that occur on irradiation under both an electron fluence and flux by presenting results from a series of molecular crystals. We discuss the choice of electron beam accelerating voltage and detectors for optimizing resolution and outline the different strategies employed for low-dose microscopy in relation to the damage processes in operation. In particular, we discuss the use of scanning TEM (STEM) techniques for maximizing information content from high-resolution imaging and spectroscopy of minerals and molecular crystals. We suggest how this understanding can then be carried forward for in-situ analysis of samples interacting with liquids and gases, provided any electron beam-induced alteration of a specimen is controlled or used to drive a chosen reaction. Finally, we demonstrate that cryo-TEM of nanoparticle samples snap-frozen in vitreous ice can play a significant role in benchmarking dynamic processes at higher resolution. This article is part of a discussion meeting issue ‘Dynamic in situ microscopy relating structure and function’.

scholarly journals Visualizing Ligand-Mediated Bimetallic Nanocrystal Formation Pathways with In Situ Liquid Phase Transmission Electron Microscopy Synthesis

2020 ◽  
Author(s):  
Mei Wang ◽  
Asher Leff ◽  
Yue Li ◽  
Taylor Woehl
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Ex Situ ◽  
Formation Mechanisms ◽  
Transmission Electron ◽  
Thiolate Complexes ◽  
Nanocrystal Formation ◽  
Phase Transmission

Colloidal synthesis of alloyed multimetallic nanocrystals with precise composition control remains a challenge and a critical missing link in theory-driven rational design of functional nanomaterials. Liquid phase transmission electron microscopy (LP-TEM) enables directly visualizing nanocrystal formation mechanisms that can inform discovery of design rules for colloidal multimetallic nanocrystal synthesis, but it remains unclear whether the salient chemistry of the flask synthesis is preserved in the extreme electron beam radiation environment during LPTEM. Here we demonstrate controlled in situ LP-TEM synthesis of alloyed AuCu nanoparticles while maintaining the molecular structure of electron beam sensitive metal thiolate precursor complexes. Ex situ flask synthesis experiments showed that nearly equimolar AuCu alloys formed from heteronuclear metal thiolate complexes, while gold-rich alloys formed in their absence. Systematic dose rate-controlled in situ LP-TEM synthesis experiments established a range of electron beam synthesis conditions that formed alloyed AuCu nanoparticles with similar alloy composition, random alloy structure, and particle size distribution shape as those from ex situ flask synthesis, indicating metal thiolate complexes were preserved under these conditions. Reaction kinetic simulations of radical-ligand reactions revealed that polymer capping ligands acted as effective hydroxyl radical scavengers during LP-TEM synthesis and prevented metal thiolate oxidation at low dose rates. In situ synthesis experiments and ex situ atomic scale imaging revealed that a key role of metal thiolate complexes was to prevent copper atom oxidation and facilitate formation of prenucleation cluster intermediates. This work demonstrates that complex ion precursor chemistry can be maintained during LP-TEM imaging, enabling probing nanocrystal formation mechanisms with LP-TEM under reaction conditions representative of ex situ flask synthesis.

Progress in environmental high-voltage transmission electron microscopy for nanomaterials

2020 ◽  
Vol 378 (2186) ◽  
pp. 20190602
Author(s):  
Nobuo Tanaka ◽  
Takeshi Fujita ◽  
Yoshimasa Takahashi ◽  
Jun Yamasaki ◽  
Kazuyoshi Murata ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Voltage ◽  
High Energy ◽  
Transmission Electron ◽  
Recent Developments ◽  
In Situ Observations ◽  
High Voltage Transmission ◽  
And Function

A new environmental high-voltage transmission electron microscope (E-HVEM) was developed by Nagoya University in collaboration with JEOL Ltd. An open-type environmental cell was employed to enable in-situ observations of chemical reactions on catalyst particles as well as mechanical deformation in gaseous conditions. One of the reasons for success was the application of high-voltage transmission electron microscopy to environmental (in-situ) observations in the gas atmosphere because of high transmission of electrons through gas layers and thick samples. Knock-on damages to samples by high-energy electrons were carefully considered. In this paper, we describe the detailed design of the E-HVEM, recent developments and various applications. This article is part of a discussion meeting issue ‘Dynamic in situ microscopy relating structure and function'.

Direct Observation of Defect Motion in Silicon By High-Resolution Transmission Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 358-359
Author(s):  
M. A. Parker ◽  
R. Sinclair
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Crystal Defects ◽  
Incident Electron Beam ◽  
Transmission Electron ◽  
Heating Effects ◽  
Electron Beam Heating

Observations of defect motion by high resolution transmission electron microscopy (HRTEM) are rare. Unfortunately, the application of this technique has been limited to a few unique materials, those that can obtain sufficient thermal energy for the initiation of atomic motion through the heating effects of the incident electron beam. In earlier work, it was speculated that events such as the motion of crystal defects, observed in cadmium telluride (CdTe) with the electron beam heating method, might become evident in materials such as silicon (Si) if only sufficiently high temperatures could be achieved (∼ 600°C) in-situ.A silicon specimen with a suitable population of defects was chosen for examination; it consisted of a cross-section of.3 μ ﹛100﹜ silicon on ﹛1102﹜ sapphire (SOS from Union Carbide) which was implant amorphized by 28Si+ ion implantation at an energy of ∼ 170keV.

In situ Transmission Electron Microscopy Studies on Structural Dynamics of Transition Metal Nanoclusters

2005 ◽  
Vol 20 (7) ◽  
pp. 1785-1791 ◽  
Author(s):  
T. Vystavel ◽  
S.A. Koch ◽  
G. Palasantzas ◽  
J.Th.M. De Hosson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Transition Metal ◽  
Electron Beam Irradiation ◽  
Oxide Shell ◽  
Metal Nanoclusters ◽  
Beam Irradiation ◽  
Transmission Electron

The structural stability of transition metal nanoclusters has been scrutinized with in situ transmission electron microscopy as a function of temperature. In particular iron, cobalt, niobium, and molybdenum clusters with diameters around 5 nm have been investigated. During exposure to air, a thin oxide shell with a thickness of 2 nm is formed around the iron and cobalt clusters, which is thermally unstable under moderate high vacuum annealing above 200 °C. Interestingly, niobium clusters oxidize only internally at higher temperatures without the formation of an oxide shell. They are unaffected under electron beam irradiation, whereas iron and cobalt undergo severe structural changes. Further, no cluster coalescence of niobium takes place, even during annealing up to 800 °C, whereas iron and cobalt clusters coalesce after decomposition of the oxide, as long as the clusters are in close contact. In contrast to niobium, molybdenum clusters do not oxidize upon annealing; they are stable under electron beam irradiation and coalesce at temperatures higher than 800 °C. In all cases, the coalescence process indicates a strong influence of the local environment of the cluster.

scholarly journals Accessing local electron-beam induced temperature changes during in situ liquid-phase transmission electron microscopy

2021 ◽  
Author(s):  
Birk Fritsch ◽  
Andreas Hutzler ◽  
Mingjian Wu ◽  
Saba Khadivianazar ◽  
Lilian Vogl ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Liquid Phase ◽  
Gas Bubble ◽  
Local Electron ◽  
Temperature Changes ◽  
Transmission Electron ◽  
Phase Transmission

Electron-beam induced heating in the vicinity of a gas bubble in liquid-phase TEM is quantified in situ.

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