scholarly journals Resolving hydrogen atoms at metal-metal hydride interfaces

2020 ◽  
Vol 6 (5) ◽  
pp. eaay4312 ◽  
Author(s):  
Sytze de Graaf ◽  
Jamo Momand ◽  
Christoph Mitterbauer ◽  
Sorin Lazar ◽  
Bart J. Kooi
Keyword(s):  
Metal Hydride ◽  
Phase Contrast ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Hydrogen Atoms ◽  
Volumetric Density ◽  
Transmission Electron ◽  
Metal Metal ◽  
Scanning Transmission ◽  
Differential Phase Contrast

Hydrogen as a fuel can be stored safely with high volumetric density in metals. It can, however, also be detrimental to metals, causing embrittlement. Understanding fundamental behavior of hydrogen at the atomic scale is key to improve the properties of metal-metal hydride systems. However, currently, there is no robust technique capable of visualizing hydrogen atoms. Here, we demonstrate that hydrogen atoms can be imaged unprecedentedly with integrated differential phase contrast, a recently developed technique performed in a scanning transmission electron microscope. Images of the titanium-titanium monohydride interface reveal stability of the hydride phase, originating from the interplay between compressive stress and interfacial coherence. We also uncovered, 30 years after three models were proposed, which one describes the position of hydrogen atoms with respect to the interface. Our work enables previously unidentified research on hydrides and is extendable to all materials containing light and heavy elements, including oxides, nitrides, carbides, and borides.

Electron Microscopy Studies of The Chemistry And Microstructure of BaF2 / YBa2Cu3O7-x Thin Films

1994 ◽  
Vol 52 ◽  
pp. 796-797
Author(s):  
J. L. Lee ◽  
C. A. Weiss ◽  
R. A. Buhrman ◽  
J. Silcox
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Island Growth ◽  
Multilayer Systems ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Mgo Substrate

BaF2 thin films are being investigated as candidates for use in YBa2Cu3O7-x (YBCO) / BaF2 thin film multilayer systems, given the favorable dielectric properties of BaF2. In this study, the microstructural and chemical compatibility of BaF2 thin films with YBCO thin films is examined using transmission electron microscopy and microanalysis. The specimen was prepared by using laser ablation to first deposit an approximately 2500 Å thick (0 0 1) YBCO thin film onto a (0 0 1) MgO substrate. An approximately 7500 Å thick (0 0 1) BaF2 thin film was subsequendy thermally evaporated onto the YBCO film.Images from a VG HB501A UHV scanning transmission electron microscope (STEM) operating at 100 kV show that the thickness of the BaF2 film is rather uniform, with the BaF2/YBCO interface being quite flat. Relatively few intrinsic defects, such as hillocks and depressions, were evident in the BaF2 film. Moreover, the hillocks and depressions appear to be faceted along {111} planes, suggesting that the surface is smooth and well-ordered on an atomic scale and that an island growth mechanism is involved in the evolution of the BaF2 film.

Electrostatic potential imaging of phase-separated structures in organic materials via differential phase contrast scanning transmission electron microscopy

Microscopy ◽  
2020 ◽  
Vol 69 (5) ◽  
pp. 304-311
Author(s):  
Shin Inamoto ◽  
Satoru Shimomura ◽  
Yuji Otsuka
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electrostatic Potential ◽  
Scanning Transmission Electron Microscopy ◽  
Phase Contrast ◽  
Organic Materials ◽  
Differential Phase ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Differential Phase Contrast

Abstract Electron staining is generally performed prior to observing organic materials via transmission electron microscopy (TEM) to enhance image contrast. However, electron staining can deteriorate organic materials. Here, we demonstrate electrostatic potential imaging of organic materials via differential phase contrast (DPC) scanning transmission electron microscopy (STEM) without electron staining. Electrostatic potential imaging drastically increases the contrast between different materials. Phase-separated structures in a poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend that are impossible to observe using conventional STEM are clearly visualized. Furthermore, annealing behavior of the phase-separated structures is directly observed. The morphological transformations in the samples are consistent with their physical parameters, including their glass transition and melting temperatures. Our results indicate that electrostatic potential imaging is highly effective for observing organic materials.

scholarly journals Flexible STEM with Simultaneous Phase and Depth Contrast

2021 ◽  
pp. 1-12
Author(s):  
Shahar Seifer ◽  
Lothar Houben ◽  
Michael Elbaum
Keyword(s):  
System Integration ◽  
Scanning Transmission Electron Microscopy ◽  
Phase Contrast ◽  
Wide Field ◽  
Analog To Digital ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Differential Phase Contrast ◽  
Flexible Stem ◽  
Contrast Image

Recent advances in scanning transmission electron microscopy (STEM) have rekindled interest in multi-channel detectors and prompted the exploration of unconventional scan patterns. These emerging needs are not yet addressed by standard commercial hardware. The system described here incorporates a flexible scan generator that enables exploration of low-acceleration scan patterns, while data are recorded by a scalable eight-channel array of nonmultiplexed analog-to-digital converters. System integration with SerialEM provides a flexible route for automated acquisition protocols including tomography. Using a solid-state quadrant detector with additional annular rings, we explore the generation and detection of various STEM contrast modes. Through-focus bright-field scans relate to phase contrast, similarly to wide-field TEM. More strikingly, comparing images acquired from different off-axis detector elements reveals lateral shifts dependent on defocus. Compensation of this parallax effect leads to decomposition of integrated differential phase contrast (iDPC) to separable contributions relating to projected electric potential and to defocus. Thus, a single scan provides both a computationally refocused phase contrast image and a second image in which the signed intensity, bright or dark, represents the degree of defocus.

scholarly journals Toward quantitative electromagnetic field imaging by differential-phase-contrast scanning transmission electron microscopy

Microscopy ◽  
2020 ◽  
Author(s):  
Takehito Seki ◽  
Yuichi Ikuhara ◽  
Naoya Shibata
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electromagnetic Field ◽  
Scanning Transmission Electron Microscopy ◽  
Phase Contrast ◽  
Differential Phase ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Differential Phase Contrast ◽  
Field Imaging

Abstract Differential-phase-contrast scanning transmission electron microscopy (DPC STEM) is a technique to directly visualize local electromagnetic field distribution inside materials and devices at very high spatial resolution. Owing to the recent progress in the development of high-speed segmented and pixelated detectors, DPC STEM now constitutes one of the major imaging modes in modern aberration-corrected STEM. While qualitative imaging of electromagnetic fields by DPC STEM is readily possible, quantitative imaging by DPC STEM is still under development because of the several fundamental issues inherent in the technique. In this report, we review the current status and future prospects of DPC STEM for quantitative electromagnetic field imaging from atomic scale to mesoscopic scale.

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