scholarly journals Characterization of Sulfur and Nanostructured Sulfur Battery Cathodes in Electron Microscopy Without Sublimation Artifacts

2017 ◽  
Vol 23 (1) ◽  
pp. 155-162 ◽  
Author(s):  
Barnaby D.A. Levin ◽  
Michael J. Zachman ◽  
Jörg G. Werner ◽  
Ritu Sahore ◽  
Kayla X. Nguyen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Vacuum ◽  
Lithium Ion ◽  
Multiple Length Scales ◽  
Transmission Electron ◽  
Nanoscale Characterization ◽  
Infusion Method ◽  
Electron Microscopes ◽  
Sulfur Battery

AbstractLithium sulfur (Li–S) batteries have the potential to provide higher energy storage density at lower cost than conventional lithium ion batteries. A key challenge for Li–S batteries is the loss of sulfur to the electrolyte during cycling. This loss can be mitigated by sequestering the sulfur in nanostructured carbon–sulfur composites. The nanoscale characterization of the sulfur distribution within these complex nanostructured electrodes is normally performed by electron microscopy, but sulfur sublimates and redistributes in the high-vacuum conditions of conventional electron microscopes. The resulting sublimation artifacts render characterization of sulfur in conventional electron microscopes problematic and unreliable. Here, we demonstrate two techniques, cryogenic transmission electron microscopy (cryo-TEM) and scanning electron microscopy in air (airSEM), that enable the reliable characterization of sulfur across multiple length scales by suppressing sulfur sublimation. We use cryo-TEM and airSEM to examine carbon–sulfur composites synthesized for use as Li–S battery cathodes, noting several cases where the commonly employed sulfur melt infusion method is highly inefficient at infiltrating sulfur into porous carbon hosts.

scholarly journals Micro and Nanoscale Characterization of Complex Multilayer-Structured White Etching Layer in Rails

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 749 ◽  
Author(s):  
Jun Wu ◽  
Roumen Petrov ◽  
Sebastian Kölling ◽  
Paul Koenraad ◽  
Loic Malet ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rail Steel ◽  
Electron Backscatter Diffraction ◽  
Thickness Distribution ◽  
Atom Probe ◽  
Transmission Electron ◽  
Nanoscale Characterization ◽  
Scale Characterization

Micro- to nano-scale characterization of the microstructures in the white etching layer (WEL), observed in a Dutch R260 Mn grade rail steel, was performed via various techniques. Retained austenite in the WEL was identified via electron backscatter diffraction (EBSD), automatic crystallographic orientation mapping in transmission electron microscopy (ACOM-TEM), and X-ray diffraction (XRD). EBSD and ACOM-TEM methods were used to quantify grains (size range: 50 nm–4 μm) in the WEL. Transmission electron microscopy (TEM) was used to identify complex heterogeneous microstructural morphologies in the WEL: Nano-twinning substructure with high dislocation density in the WEL close to the rail surface and untransformed cementite and dislocations in the WEL close to the pearlite matrix. Furthermore, atom probe tomography (APT) revealed a heterogeneous through-thickness distribution of alloying elements in the WEL. Accordingly, the WEL is considered a multi-layered martensitic microstructure. These findings are supported by the temperature calculations from the shape analysis of the manganese profile from APT measurements, related to manganese diffusion. The deformation characteristics of the WEL and the pearlite beneath the WEL are discussed based on the EBSD measurements. The role of deformation in the martensitic phase transformation for WEL formation is discussed.

An Environmental Transmission Electron Microscope for in situ Synthesis and Characterization of Nanomaterials

2005 ◽  
Vol 20 (7) ◽  
pp. 1695-1707 ◽  
Author(s):  
Renu Sharma
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Elevated Temperatures ◽  
Dark Field ◽  
In Situ Synthesis ◽  
Synthesis And Characterization ◽  
Transmission Electron ◽  
Electron Microscopes

The world of nanomaterials has become the real world for most applications in the area of nanotechnology. As postsynthesis handling of materials at the nanoscale level is impractical, nanomaterials must be synthesized directly as part of a device or circuit. The demands of nanotechnology have led to modifications in the design of transmission electron microscopes (TEMs) that enable in situ synthesis and characterization simultaneously. The environmental TEM (ETEM) is one such modified instrument that has often been used to follow gas–solid and/or liquid–solid interactions at elevated temperatures. Although the history and development of the ETEM, also called the controlled atmosphere or environmental cell TEM, is as old as transmission electron microscopy itself, developments in the design of medium-voltage TEMs have succeeded in bringing resolutions down to the subnanometer level. A modern ETEM equipped with a field-emission gun, energy filter or electron energy-loss spectrometer, scanning transmission electron microscopy coils, and bright-field and dark-field detectors can be a versatile tool for understanding chemical processes at the nanometer level. This article reviews the design and operations of a dedicated ETEM. Its applications range from the in situ characterization of reaction steps, such as oxidation-reduction and hydroxylation, to the in situ synthesis of nanomaterials, such as quantum dots and carbon nanotubes. Some examples of the current and the future applications for the synthesis and characterization of nanomaterials are also discussed.

Structural Characterization of Reaction Product Region in Al/MgO and Al/MgAl2O4 Systems

2011 ◽  
Vol 172-174 ◽  
pp. 1273-1278 ◽  
Author(s):  
Rafal Nowak ◽  
Natalia Sobczak ◽  
Edmund Sienicki ◽  
Jerzy Morgiel
Keyword(s):  
Electron Microscopy ◽  
Single Crystals ◽  
High Vacuum ◽  
Single Layer ◽  
Oxide Phase ◽  
Metallic Phase ◽  
Ultra High Vacuum ◽  
Transmission Electron ◽  
Oxide Particles

The reaction product region, formed between molten aluminium and MgO and MgAl2O4 single crystals of three different crystallographic orientations, was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) coupled with X-ray energy dispersive spectrometry (EDS). The Al/MgO and Al/MgAl2O4 couples were produced under ultra high vacuum at 800, 900 and 1000°C. The observations proved the redox reactions of Al with both MgO and MgAl2O4. Independently of crystallographic orientation of initial oxide single crystals, the reaction product region (RPR) was formed and it was built of oxide particles surrounded by continuous metallic phase. For Al/MgO couples, the RPR was composed of two layers, where in the first layer, the oxide phase was Al2O3 while in the second layer, the MgAl2O4 was identified. In the case of Al/MgAl2O4 couples, a single layer was distinguished and only the Al2O3 phase was recognized.

Structural Characterization of Carbon Materials Prepared at Low Temperature

1995 ◽  
Vol 393 ◽  
Author(s):  
Xiang-Yun Song ◽  
Xi Chu ◽  
Kimio Kinoshita
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phenol Formaldehyde ◽  
High Capacity ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
High Degree

ABSTRACTHigh-capacity carbon electrodes for rechageable lithium-ion batteries were prepared by carbonization of thermosetting resins such as phenol-formaldehyde at temperatures between 500°C and 600°C. Their structures were characterized by high resolution transmission electron microscopy, in-situ transmission electron microscopy and x-ray diffraction analysis. These studies suggest that the carbons consist predominantly of disorganized (amorphous) phase. However evidence was found in carbon containing nickel cobalt oxide for the presence of organized graphite-like regions of parallel and curved layer planes. These graphitized structure usually appear as agglomerate particles which are composed of many smaller (100-nm diameter) particles. The high degree of graphitization is attributed to catalytic graphitization that occurs in the presence of the metal oxide.

High-speed nanoscale characterization of dewetting via dynamic transmission electron microscopy

2016 ◽  
Vol 120 (8) ◽  
pp. 085301 ◽  
Author(s):  
Sahar Hihath ◽  
Melissa K. Santala ◽  
Geoffrey Campbell ◽  
Klaus van Benthem
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Speed ◽  
Transmission Electron ◽  
Nanoscale Characterization
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