In-Situ TEM Observation for Dehydrogenation Mechanism in MgH2 with Catalyst

2010 ◽  
Vol 654-656 ◽  
pp. 2867-2870 ◽  
Author(s):  
Eri Morita ◽  
Akifumi Ono ◽  
Shigehito Isobe ◽  
Yong Ming Wang ◽  
Naoyuki Hashimoto ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Catalytic Effect ◽  
Hydrogen Diffusion ◽  
In Situ Observation ◽  
Transmission Electron ◽  
Milled Sample ◽  
High Resolution Images ◽  
Dehydrogenation Mechanism

We carried out in-situ observation on the catalytic effect of Nb2O5 in MgH2 by using a high voltage transmission electron microscope (HVEM). We synthesized two kinds of samples, which were prepared by ball milling and by hand mixing. In milled sample, Nb2O5 was not confirmed from high resolution images, however, NbO was identified. As the temperature increased, the decomposition of MgH2 proceeded, while Mg formed and grew. It suggested that NbO had the catalytic effect to promote the dehydrogenation of MgH2. In mixed sample, which was prepared to clearly observe the boundary between the catalyst and Mg phase, it was revealed that the dehydrogenation started from the boundary of MgH2 and Nb2O5. This result suggested that the dehydrogenation could proceed with hydrogen diffusion from MgH2 through Mg phase to the boundary.

In-situ TEM Observation for Reaction Mechanism in MgH2 Hydrogen Storage Material

2009 ◽  
Vol 1216 ◽  
Author(s):  
Akifumi Ono ◽  
Shigehito Isobe ◽  
Yongming Wang ◽  
Naoyuki Hashimoto ◽  
Somei Ohnuki
Keyword(s):  
Hydrogen Diffusion ◽  
In Situ Tem ◽  
In Situ Observation ◽  
Desorption Process ◽  
Voltage Electron ◽  
Transmission Electron ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Nano Size

AbstractIn-situ observation on the catalytic effect of Nb2O5 in MgH2 was carried out by using transmission electron microscopy (TEM). We prepared two kinds of samples, because we tried to observe the reaction from two kinds of viewpoints. MgH2 catalyzed with 1 mol% of Nb2O5 was prepared for an overall viewpoint on the desorption process of MgH2 with catalyst by conventional TEM. The dehydrogenation of the 1 mol% sample started at 150 °C and Mg nano-size particles were formed. However, Nb2O5 was not confirmed in diffraction patterns and images, because it was highly dispersed by ball-milled. So MgH2 catalyzed with 10 mol% of Nb2O5 was prepared for local viewpoint to focus the boundary between the catalyst and the Mg phase by high voltage electron micro scope (HVEM). The sample mixed in mortar was prepared for this, because it was difficult to find the boundary in the sample ball-milled. The high resolution images of the 10 mol% sample revealed that the dehydrogenation started from the interface of MgH2 and Nb2O5. The result suggested that the dehydrogenation could proceed with hydrogen diffusion from MgH2 phase to the interface between Mg and Nb2O5.

In situ TEM observations of melting in nanosized eutectic Pb-Cd inclusions embedded in Al

1996 ◽  
Vol 54 ◽  
pp. 986-987
Author(s):  
S. Hagège ◽  
U. Dahmen ◽  
E. Johnson ◽  
A. Johansen ◽  
V.S. Tuboltsev
Keyword(s):  
Electron Microscope ◽  
Melt Spinning ◽  
Ternary Alloys ◽  
Solid Matrix ◽  
Eutectic System ◽  
In Situ Tem ◽  
In Situ Observation ◽  
Orientation Relationships ◽  
Transmission Electron

Small particles of a low-melting phase embedded in a solid matrix with a higher melting point offer the possibility of studying the mechanisms of melting and solidification directly by in-situ observation in a transmission electron microscope. Previous studies of Pb, Cd and other low-melting inclusions embedded in an Al matrix have shown well-defined orientation relationships, strongly faceted shapes, and an unusual size-dependent superheating before melting.[e.g. 1,2].In the present study we have examined the shapes and thermal behavior of eutectic Pb-Cd inclusions in Al. Pb and Cd form a simple eutectic system with each other, but both elements are insoluble in solid Al. Ternary alloys of Al (Pb,Cd) were prepared from high purity elements by melt spinning or by sequential ion implantation of the two alloying additions to achieve a total alloying addition of up to lat%. TEM observations were made using a heating stage in a 200kV electron microscope equipped with a video system for recording dynamic behavior.

scholarly journals In situ electrical probing and bias-mediated manipulation of dielectric nanotubes in a high-resolution transmission electron microscope

2006 ◽  
Vol 88 (12) ◽  
pp. 123101 ◽  
Author(s):  
D. Golberg ◽  
M. Mitome ◽  
K. Kurashima ◽  
C. Y. Zhi ◽  
C. C. Tang ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Transmission Electron Microscope ◽  
Transmission Electron

Silica Encapsulated CdS Tabular Nanocomposites via a Template Directed Agglomeration Mechanism

2008 ◽  
Vol 8 (11) ◽  
pp. 5878-5886 ◽  
Author(s):  
Jun Wang ◽  
Stephen J. Sollenberger ◽  
Ying Yuan ◽  
Timothy J. Yosenick ◽  
James H. Adair
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Coating Layer ◽  
Layer Growth ◽  
Cds Nanoparticles ◽  
Atomic Force ◽  
Transmission Electron ◽  
Potential Applications ◽  
Hydrolysis Of

Silica coated CdS tabular nanocomposites were synthesized through precipitation of CdS nanoparticles in octylamine/water bilayer system followed by in situ hydrolysis of tetraethoxylsilicate (TEOS) precursor. Face diameter of the nanoplatelets was in the range of 50∼250 nm with a variable thickness (3 to 25 nm) dictated by octylamine content or R ratio ([water]/[octylamine]). A uniform SiO2 outer shell of about 15 nm was observed regardless of the size of the high aspect ratio CdS nanoplatelets, which appeared to be agglomerated primarily owing to the confined bilayer template. Morphology and microstructure of the CdS/SiO2 tabular nanocomposites were characterized using atomic force microscope (AFM) and high resolution transmission electron microscope (HRTEM). A noticeable enhancement in absorbance for the UV-vis spectra was observed due to the SiO2 coating layer. Growth mechanism of nanocomposite platelets and potential applications associated with this anisotropic nanocomposite are discussed.

In situ observation of the motion of ferroelectric domain walls in Bi4Ti3O12 single crystals

2016 ◽  
Vol 49 (5) ◽  
pp. 1645-1652 ◽  
Author(s):  
Wanneng Ye ◽  
Lingli Tang ◽  
Chaojing Lu ◽  
Huabing Li ◽  
Yichun Zhou
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Single Crystals ◽  
Transmission Electron Microscope ◽  
Domain Walls ◽  
Domain Switching ◽  
Ferroelectric Domain ◽  
In Situ Observation ◽  
Transmission Electron

Five types of ferroelectric domain walls (DWs) are present in Bi4Ti3O12 single crystals (Ye et al., 2015). Here their motion was investigated in situ using transmission electron microscopy and optical microscopy. The motion of P (a)-90° DWs, P (a)-180° DWs and P (c)-180° DWs was observed through electron beam poling in a transmission electron microscope. The growth of new P s(a)-180° nanodomains was frequently seen and they tended to nucleate at preexisting P s(a)-90° DWs. Irregularly curved P (c)-180° DWs exhibit the highest mobility, while migration over a short range occurs occasionally for faceted P s(a)-90° DWs. In addition, the motion of P s(a)-90° DWs and the growth/annihilation of new needle-like P s(a)-90° domains in a 20 µm-thick crystal were observed under an external electric field on an optical microscope. Most of the new needle-like P s(a)-90° domains nucleate at preexisting P s(a)-90° DWs and the former are much smaller than the latter. This is very similar to the situation for P s(a)-180° domain switching induced by electron beam poling in a transmission electron microscope. Our observations suggest the energy hierarchy for different domains of P s(c)-180° ≤ P s(a)-180° ≤ P s(a)-90° ≤ new needle-like P s(a)-90° in ferroelectric Bi4Ti3O12.

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