scholarly journals Investigation of Deoxidation Process of MoO3 Using Environmental TEM

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 56
Author(s):  
Peijie Ma ◽  
Ang Li ◽  
Lihua Wang ◽  
Kun Zheng
Keyword(s):  
Thermal Field ◽  
Lattice Structure ◽  
Structural Evolution ◽  
Transmission Electron ◽  
Deoxidation Process ◽  
Catalytic Material ◽  
Environmental Tem ◽  
Nano Catalysts ◽  
Electron Energy Loss

In situ environmental transmission electron microscope (ETEM) could provide intuitive and solid proof for the local structure and chemical evolution of materials under practical working conditions. In particular, coupled with atmosphere and thermal field, the behavior of nano catalysts could be directly observed during the catalytic reaction. Through the change of lattice structure, it can directly correlate the relationship between the structure, size and properties of materials in the nanoscale, and further directly and accurately, which is of great guiding value for the study of catalysis mechanism and the optimization of catalysts. As an outstanding catalytic material in the application of methane reforming, molybdenum oxide (MoO3)-based materials and its deoxidation process were studied by in situ ETEM method. The corresponding microstructures and components evolution were analyzed by diffraction, high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectrum (EELS) techniques. MoO3 had a good directional deoxidation process accompanied with the process of nanoparticles crushing and regrowth in hydrogen (H2) and thermal field. However, in the absence of H2, the samples would exhibit different structural evolution.

Investigation of Switching Mechanism in HfO2-Based Oxide Resistive Memories by In-Situ Transmission Electron Microscopy and Electron Energy Loss Spectroscopy

2017 ◽  
Author(s):  
T. Dewolf ◽  
D. Cooper ◽  
N. Bernier ◽  
V. Delaye ◽  
A. Grenier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Hafnium Dioxide ◽  
Switching Mechanism ◽  
Transmission Electron ◽  
Electron Energy Loss

Abstract Forming and breaking a nanometer-sized conductive area are commonly accepted as the physical phenomenon involved in the switching mechanism of oxide resistive random access memories (OxRRAM). This study investigates a state-of-the-art OxRRAM device by in-situ transmission electron microscopy (TEM). Combining high spatial resolution obtained with a very small probe scanned over the area of interest of the sample and chemical analyses with electron energy loss spectroscopy, the local chemical state of the device can be compared before and after applying an electrical bias. This in-situ approach allows simultaneous TEM observation and memory cell operation. After the in-situ forming, a filamentary migration of titanium within the dielectric hafnium dioxide layer has been evidenced. This migration may be at the origin of the conductive path responsible for the low and high resistive states of the memory.

scholarly journals Imaging the Polymorphic Transformation in a Single Cu6Sn5 Grain in a Solder Joint

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2229 ◽  
Author(s):  
Flora Somidin ◽  
Hiroshi Maeno ◽  
Xuan Tran ◽  
Stuart D. McDonald ◽  
Mohd Mohd Salleh ◽  
...  
Keyword(s):  
Solder Joint ◽  
Polymorphic Transformation ◽  
Structural Evolution ◽  
Real Space ◽  
Transformation Behavior ◽  
New Approach ◽  
Transmission Electron ◽  
Contrast Pattern ◽  
In Situ Observations

In-situ observations of the polymorphic transformation in a single targeted Cu6Sn5 grain constrained between Sn-0.7 wt % Cu solder and Cu-Cu3Sn phases and the associated structural evolution during a solid-state thermal cycle were achieved via a high-voltage transmission electron microscope (HV-TEM) technique. Here, we show that the monoclinic η′-Cu6Sn5 superlattice reflections appear in the hexagonal η-Cu6Sn5 diffraction pattern upon cooling to isothermal 140 °C from 210 °C. The in-situ real space imaging shows that the η′-Cu6Sn5 contrast pattern is initiated at the grain boundary. This method demonstrates a new approach for further understanding the polymorphic transformation behavior on a real solder joint.

Design and Applications of Environmental Cell Transmission Electron Microscope for In Situ Observations of Gas–Solid Reactions

2001 ◽  
Vol 7 (6) ◽  
pp. 494-506 ◽  
Author(s):  
Renu Sharma
Keyword(s):  
Chemical Vapor ◽  
Atomic Level ◽  
Chemical Information ◽  
Oxidation Reduction ◽  
Transmission Electron ◽  
Recent Developments ◽  
Level Information ◽  
Resolution Imaging ◽  
Electron Energy Loss

AbstractThe environmental transmission electron microscopy (E-TEM) is a budding technique for in situ study of gas–solid chemical reactions with numerous applications. Recent improvements in the design have made it possible not only to obtain atomic level information but also the chemical information during the reaction by incorporating an imaging filter or electron energy-loss spectrometer to an E-TEM. We have been involved in modifying a couple of microscopes to incorporate environmental cells in order to convert them into E-TEMs. These microscopes have been used to obtain atomic level information of the structural and chemical changes during dynamic processes by in situ electron diffraction, high-resolution imaging, and electron energyloss spectroscopy. The applications include, but are not limited to, oxidation, reduction, polymerization, nitridation, dehydroxylation, hydroxylation, chemical vapor deposition, etc. We report recent developments in the design and application along with the limitations of an E-TEM.

Direct UHV-TEM Observation of Palladium Clusters on a Silicon Surface

2004 ◽  
Vol 10 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Masaki Takeguchi ◽  
Kazutaka Mitsuishi ◽  
Miyoko Tanaka ◽  
Kazuo Furuya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Layer ◽  
Silicon Surface ◽  
Lattice Structure ◽  
Plan View ◽  
Palladium Clusters ◽  
Transmission Electron ◽  
Pd Clusters

About 1 monolayer of palladium was deposited onto a silicon (111) 7 × 7 surface at a temperature of about 550 K inside an ultrahigh vacuum transmission electron microscope, resulting in formation of Pd2Si nanoislands and a 1 × 1 surface layer. Pd clusters created from an excess of Pd atoms on the 1 × 1 surface layer were directly observed byin situplan view high-resolution transmission electron microscopy. When an objective aperture was introduced so that electron diffractions less than 0.20 nm were filtered out, the lattice structure of the 1 × 1 surface with 0.33 nm spacing and the Pd clusters with a trimer shape were visualized. It was found that image contrast of the 1 × 1 lattice on the specific height terraces disappeared, and thereby an atomic structure of the Pd clusters was clearly observed. The appearance and disappearance of the 1 × 1 lattice was explained by the effect of the kinematical diffraction. It was identified that a Pd cluster was composed of three Pd atoms without a centered Si atom, which is consistent with the model proposed previously. The feature of the Pd clusters stuck at the surface step was also described.

A Novel Technique for Determining Local Dielectric Function During Ferroelectric to Paraelectric Phase Transformation in Barium Titanate with a Transmission Eels

1995 ◽  
Vol 404 ◽  
Author(s):  
Kalpana S Katti ◽  
Maoxu Qian ◽  
Mehmet Sarikaya
Keyword(s):  
Phase Transformation ◽  
Barium Titanate ◽  
Energy Loss ◽  
Electron Energy ◽  
Dielectric Function ◽  
Optical Parameters ◽  
Edge Structure ◽  
Transmission Electron ◽  
Electron Energy Loss

AbstractIn this work a transmission electron microscopy (TEM) technique was used in obtaining local dielectric properties calculated from optical parameters for dynamic investigation of the effect of cubic to tetragonal phase transformation in barium titanate. In order to obtain in situ local dielectric during phase transformation, Kramers-Kronig relations were applied using the transmission electron energy loss (EELS) measurements. The optical excitations in the EELS spectra were consistent with the band structure results. The Re (1/ε) (real part of the dielectric function) obtained from the energy loss data indicated a change at the phase transformation. A broadening of the valence plasmon excitation suggested an order-disorder nature to the cubic to tetragonal transformation. In situ electron energy loss near edge structure (ELNES) studies from 500–700 eV energy range near the O-K edge exhibited a pre-edge feature that is associated with the Ti-L1, edge which further indicates an order-disorder nature to the phase transformation. The significance of the results is discussed.

Development of Wet Environmental TEM (Wet-ETEM) for In Situ Studies of Liquid-Catalyst Reactions on the Nanoscale

2002 ◽  
Vol 8 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Pratibha L. Gai
Keyword(s):  
Biological Sciences ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Transmission Electron ◽  
Wide Range ◽  
Environmental Tem ◽  
Nanoscale Imaging ◽  
Solution Gas

We present the development of in situ wet environmental transmission electron microscopy (Wet-ETEM) for direct probing of controlled liquid–catalyst reactions at operating temperatures on the nanoscale. The first nanoscale imaging and electron diffraction of dynamic liquid hydrogenation and polymerization reactions in the manufacture of polyamides reported here opens up new opportunities for high resolution studies of a wide range of solution–solid and solution–gas–solid reactions in the chemical and biological sciences.

scholarly journals Enabling Lab-in-Gap Transmission Electron Microscopy at Atomic Resolution

2016 ◽  
Vol 24 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Xiao Feng Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Pole Piece ◽  
Large Area ◽  
Electrical Fields ◽  
Transmission Electron ◽  
Environmental Tem ◽  
New Generation

Abstract: Hitachi Lab-in-Gap transmission electron microscopy (TEM) technologies are introduced. The term Lab-in-Gap refers to a special function that allows in situ and in operando TEM studies of materials in gas or liquid environments while stimulations, such as thermal or electrical fields, are applied to the specimen sitting in the pole piece gap in a TEM system. Physical or chemical process can be activated and imaged in real time using TEM or other imaging modes. The new generation environmental TEM platform with large pole piece gap and advanced aberration correctors opens wide possibilities for integrating multiple stimuli sources as well as large-area, sub-Å resolution live imaging for dynamic structural changes.

scholarly journals Applications of in situ electron microscopy in oxygen electrocatalysis

2022 ◽  
Author(s):  
Zhi-Peng Wu ◽  
Hui Zhang ◽  
Cailing Chen ◽  
Guanxing Li ◽  
Yu Han
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Degradation Mechanism ◽  
Structural Evolution ◽  
Reduction Reaction ◽  
Future Research ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
In Situ Electron Microscopy

Oxygen electrocatalysis involving the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a vital role in cutting-edge energy conversion and storage technologies. In situ studies of the evolution of catalysts during oxygen electrocatalysis can provide important insights into their structure - activity relationships and stabilities under working conditions. Among the various in situ characterization tools available, in situ electron microscopy has the unique ability to perform structural and compositional analyzes with high spatial resolution. In this review, we present the latest developments in in situ and quasi-in situ electron microscopic techniques, including identical location electron microscopy, in situ liquid cell (scanning) transmission electron microscopy and in situ environmental transmission electron microscopy, and elaborate their applications in the ORR and OER. Our discussion centers on the degradation mechanism, structural evolution and structure - performance correlations of electrocatalysts. Finally, we summarize the earlier discussions and share our perspectives on the current challenges and future research directions of using in situ electron microscopy to explore oxygen electrocatalysis and related processes.

Kinetics of Oxygen Diffusion into Multilayer Ceramic Capacitors during the Re-Oxidation Process and its Implications on Dielectric Properties

2011 ◽  
Vol 485 ◽  
pp. 43-46
Author(s):  
Kazumi Kaneda ◽  
Youichi Mizuno ◽  
Niall J. Donnelly ◽  
Soonil Lee ◽  
Wei Guo Qu ◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
Equivalent Circuit Model ◽  
Chemical Diffusion ◽  
Circuit Model ◽  
Impedance Change ◽  
Multilayer Ceramic Capacitors ◽  
Transmission Electron ◽  
Electron Energy Loss ◽  
Kinetics Of

Re-oxidation is an important thermal process to minimize oxygen vacancies and produce high reliable Ni-MLCCs. The re-oxidation of these devices is then investigated with a series of “in-situ” impedance measurements between 400 and 500 °C in air. From the relative impedance change, chemical diffusion coefficients, associated activation energy and effective equivalent circuit model are determined. Those values were found to be reasonable compared with previous researchers’ data. Moreover, the proposed effective equivalent circuit model successfully represents the real Ni-MLCC morphology. From transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS), it is found that the electrical properties and reliabilities of the Ni-MLCCs re-oxidized under different conditions are identical.

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