Novel Ultrathin Mg Nanoblades for Hydrogen Storage

2009 ◽  
Vol 1216 ◽  
Author(s):  
Fu Tang ◽  
Gwo Ching Wang ◽  
Toh-Ming Lu
Keyword(s):  
Electron Microscopy ◽  
Thermal Desorption Spectroscopy ◽  
High Energy ◽  
Oblique Angle ◽  
Temperature Dependent ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Composition Changes ◽  
Microscopy Images

AbstractWe describe the growth of novel ultrathin Mg crystalline nanoblades by oblique angle vapor deposition. These nanoblades were then coated with catalyst Pd and hydrogenated into magnesium hydride MgH2. In situ thermal desorption spectroscopy study showed a low H desorption temperature at ∼365 K. In situ reflection high energy electron diffraction patterns were used to study the temperature dependent structure and composition changes during the de-hydrogenation of Pd coated MgH2 nanoblades. The diffraction rings reveal the formation of alloys of Pd and Mg when the temperature is over ∼480 K. Transmission electron microscopy diffraction also supports the formation of Pd and Mg alloys. This alloying reduces the cycling capability of Mg hydride. The de-hydrogenation of MgH2 introduces a strain at the bilayer interface between MgH2 and Mg resultant from 30% volume reduction from MgH2 to Mg and formed curved nanoblades as evident by scanning electron microscopy images. Designing factors of recyclable simple hydrides will be discussed.

Effects of High-Energy Ions on Synthetic Quartz

1972 ◽  
Vol 30 ◽  
pp. 544-545
Author(s):  
Joseph J. Comer ◽  
Charles Bergeron ◽  
Lester F. Lowe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Energy ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
High Energy Ions ◽  
Diffraction Patterns ◽  
Dauphiné Twinning ◽  
Beam Damage

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

Visualization of regulated nucleation and growth of lithium sulfides for high energy lithium sulfur batteries

2019 ◽  
Vol 12 (10) ◽  
pp. 3144-3155 ◽  
Author(s):  
Zheng-Long Xu ◽  
Sung Joo Kim ◽  
Donghee Chang ◽  
Kyu-Young Park ◽  
Kyun Seong Dae ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Energy ◽  
Nucleation And Growth ◽  
Transmission Electron ◽  
Lithium Sulfur Batteries ◽  
Lithium Sulfur

The nucleation and growth of lithium sulfides are directly observed by liquid in situ transmission electron microscopy.

scholarly journals Synthesis of Novel YbxSb2 − xTe3Hexagonal Nanoplates: Investigation of Their Physical, Structural, and Photocatalytic Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Younes Hanifehpour ◽  
Sang Woo Joo
Keyword(s):  
Electron Microscopy ◽  
Emission Spectra ◽  
Hydrothermal Condition ◽  
X Ray Diffraction ◽  
Dopant Content ◽  
Transmission Electron ◽  
Intensity Changes ◽  
Diffraction Patterns ◽  
Green Solution ◽  
Microscopy Images

Yb-doped Sb2Te3nanomaterials were synthesized by a coreduction method in hydrothermal condition. Powder X-ray diffraction patterns indicate that theYbxSb2−xTe3crystals (x=0.00–0.05) are isostructural with Sb2Te3. The cell parameteradecreases forYbxSb2−xTe3compounds upon increasing the dopant content (x), whilecincreases. Scanning electron microscopy and transmission electron microscopy images show that doping of Yb3+ions in the lattice of Sb2Te3produces different morphology. The electrical conductivity of Yb-doped Sb2Te3is higher than the pure Sb2Te3and increases with temperature. By increasing concentration of the Yb3+ions, the absorption spectrum of Sb2Te3shows red shifts and some intensity changes. In addition to the characteristic red emission peaks of Sb2Te3, emission spectra of doped materials show other emission bands originating fromf-ftransitions of the Yb3+ions. The photocatalytic performance of as-synthesized nanoparticles was investigated towards the decolorization of Malachite Green solution under visible light irradiation.

Microstructural properties and formation mechanisms of GaN nanorods grown on Al2O3 (0001) substrates

2009 ◽  
Vol 24 (8) ◽  
pp. 2476-2482
Author(s):  
Kyu H. Lee ◽  
Jeong Y. Lee ◽  
Y.H. Kwon ◽  
Tae W. Kang ◽  
Dong H. Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydride Vapor Phase Epitaxy ◽  
Formation Mechanisms ◽  
Gas Mixing ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Increasing Temperature ◽  
Microscopy Images

X-ray diffraction patterns, scanning electron microscopy images, and transmission electron microscopy images showed that one-dimensional GaN nanorods with [0001]-oriented single-crystalline wurtzite structures were grown on Al2O3 (0001) substrates by hydride vapor-phase epitaxy without a catalyst. The tip morphology of the GaN nanorods became flat with increasing temperature difference between the gas mixing and the substrate zones. The gas mixing temperature significantly affected the formation of the nanorods, and the substrate temperature influenced the morphology and the strain of the GaN nanorods near the GaN/Al2O3 heterointerface. The strain and the stress existing in the GaN layer near the heterointerface were decreased with increasing growth rate. The formation mechanisms of the GaN nanorods grown on the Al2O3 (0001) substrates are described on the basis of the experimental results.

In Situ Rheed and Hrem Study of Initial Stages of Interfacial Reactions of Uhv Deposited Titanium Thin Films on Silicon

1991 ◽  
Vol 222 ◽  
Author(s):  
M. H. Wang ◽  
L. J. Chen
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Energy ◽  
Interfacial Reactions ◽  
Silicide Formation ◽  
High Energy Electron ◽  
Transmission Electron ◽  
Titanium Thin Films ◽  
Amorphous Interlayer

ABSTRACTThe initial stages of interfacial reactions of ultrahigh vacuum (UHV) deposited Ti thin films on silicon have been studied by in-situ reflected high energy electron diffraction (RHEED) and transmission electron microscopy (TEM).An amorphous interlayer was found to form during the deposition of the first 1.7-nm-thick Ti layer. In samples annealed at 450 °C for 30–120 min, Ti5Si3, located at the Ti/a-interlayer interface, was identified to be the first nucleated phase. Ti5Si3, Ti5Si4, TiSi and C49-TiSi2 were observed in samples annealed at 475 °C for 30 and 60 min as well as at 500 °C for 10 and 20 min. Fundamental issues in silicide formation are discussed in light of the discovery of the formation of the amorphous interlayer and as many as four different silicide phases in the initial stages of interfacial reactions of UHV deposited Ti thin films on silicon.

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'.

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