A Reactor for “Ex-Situ” TEM Catalyst Characterization

1999 ◽  
Vol 5 (S2) ◽  
pp. 926-927 ◽  
Author(s):  
C.E. Kliewer ◽  
M.M. Disko ◽  
S.L Soled ◽  
G.J. DeMartin
Keyword(s):  
Catalytic Properties ◽  
Structural Information ◽  
High Vacuum ◽  
Chemical Characterization ◽  
Ex Situ ◽  
Catalyst Characterization ◽  
Initial Development ◽  
Transmission Electron ◽  
Pressure Variable

The microstructural and chemical characterization of catalysts is not only integral to their initial development but also to understanding and controlling their behavior over time. To better elucidate the morphology of these materials and relate physical properties to catalytic properties (e.g., activity, selectivity, etc.), “ex-situ” methods for studying catalysts under reactive conditions have been developed.Because conventional transmission electron microscopy (CTEM) is conducted under high vacuum conditions, it is difficult to replicate the exact chemical environment of a catalyst (e.g., high pressure, variable gas mixtures, etc) within the TEM. Consequently, most analyses focus on comparing “fresh” and “spent” materials. In general, this methodology provides useful structural information albeit with limitations associated with the comparison of dissimilar regions and the effects of sampling inhomogenieties.

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.

Microstructural and Chemical Characterization of Ordered Structure in Yttrium Doped Ceria

2013 ◽  
Vol 19 (1) ◽  
pp. 102-110 ◽  
Author(s):  
Pengfei Yan ◽  
Toshiyuki Mori ◽  
Yuanyuan Wu ◽  
Zhimin Li ◽  
Graeme John Auchterlonie ◽  
...  
Keyword(s):  
Chemical Characterization ◽  
Electron Microscopic Observation ◽  
Doped Ceria ◽  
Electron Microscopic ◽  
Ordered Structures ◽  
Transmission Electron ◽  
Vacancy Ordering ◽  
Crystal Model ◽  
Electron Energy Loss

AbstractThe ordered structures in different doping levels (x = 0.1, 0.15, 0.2, 0.25, 0.3) of yttrium doped ceria (YDC, Ce(1−x)YxO2−δ) electrolytes were investigated by electron diffraction, high-resolution transmission electron microscopy (TEM), scanning TEM, and electron energy loss spectroscopy. Oxygen vacancy ordering was experimentally confirmed within the ordered structures. With increasing the doping level, the concentration of trivalent Ce cations was increased in YDC samples and such trivalent Ce cations were supposed to mainly exist in the ordered structures. Based on our electron microscopic observation and microanalysis, a crystal model for the ordered structures is proposed.

scholarly journals Structure of Carbon Materials Explored by Local Transmission Electron Microscopy and Global Powder Diffraction Probes

2018 ◽  
Vol 4 (4) ◽  
pp. 68 ◽  
Author(s):  
Karolina Jurkiewicz ◽  
Mirosława Pawlyta ◽  
Andrzej Burian
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Neutron Diffraction ◽  
Carbon Materials ◽  
Structural Information ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Local Transmission

Transmission electron microscopy and neutron or X-ray diffraction are powerful techniques available today for characterization of the structure of various carbon materials at nano and atomic levels. They provide complementary information but each one has advantages and limitations. Powder X-ray or neutron diffraction measurements provide structural information representative for the whole volume of a material under probe but features of singular nano-objects cannot be identified. Transmission electron microscopy, in turn, is able to probe single nanoscale objects. In this review, it is demonstrated how transmission electron microscopy and powder X-ray and neutron diffraction methods complement each other by providing consistent structural models for different types of carbons such as carbon blacks, glass-like carbons, graphene, nanotubes, nanodiamonds, and nanoonions.

Structural Characterization of Ordered Phases in Hydrocarbon Dendrimers

1994 ◽  
Vol 351 ◽  
Author(s):  
Christopher J. Buchko ◽  
Atisa Sioshansi ◽  
Zhifu Xu ◽  
Jeffrey S. Moore ◽  
David C. Martin
Keyword(s):  
Structural Characterization ◽  
Rational Design ◽  
Structural Information ◽  
Molecular Architecture ◽  
Thermal Transitions ◽  
Self Assembling ◽  
Transmission Electron ◽  
Ordered Phases ◽  
Construction Of Self

ABSTRACTStructural characterization of phenylacetylene dendrimers (PADs) makes it possible to explore the relationship between molecular architecture and condensed phase organization. The size and geometry of the PAD series is precisely controlled, with phenylacetylene units emanating from a central phenylene in the manner of a tridendron. The branched molecule rapidly increases in size with each synthetic generation. The “shape-persistent” nature of the phenylacetylene molecule makes it ideal for use in the construction of self-assembling supramolecular systems.Transmission electron microscopy (TEM) has been used to identify the crystal structure of lower generation PADs, and wide-angle X-ray studies confirm the decrease in crystallinity with size. Hot stage optical microscopy studies of thermal transitions reveal melting points for lower generation PADs, and an apparent glass transition for the amorphous higher generations. This type of structural information is essential to the rational design of self-assembling materials.

Fabrication and Characterization of Functionally Gradient Diamondlike Carbon Coatings

1999 ◽  
Vol 594 ◽  
Author(s):  
Q. Wei ◽  
A.K. Sharma ◽  
S. Yamolenko ◽  
J. Sankar ◽  
J. Narayan
Keyword(s):  
Substrate Surface ◽  
High Vacuum ◽  
Functionally Graded ◽  
Carbon Coatings ◽  
Bonding Structure ◽  
Functionally Gradient ◽  
Transmission Electron ◽  
Alternative Approach ◽  
Diamondlike Carbon

AbstractPure diamondlike carbon thin films largely bonded by four-fold coordination suffer from a large internal compressive stress that gives rise to a serious adhesion problem. In this work, functionally gradient (FG) diamondlike carbon thin coatings were prepared by pulsed laser deposition in a high vacuum chamber as an alternative approach to address the adhesion problem of diamondlike films. Copper, silver and titanium were incorporated into the growing films with their concentration as a function of the distance from the substrate surface. The top of the thin coating is pure DLC of about 400 nm in thickness. The total thickness of the functionally graded superhard DLC coatings can exceed 1.0 μm without buckling. Visible micro-Raman spectroscopy was used to characterize the bonding structure of the layers which contain alloy atoms. High resolution transmission electron microscopy was employed to study the microstructure of the coatings. Nanoscale mechanical characterizations using Nanoindenter XP™ were carried out to study the mechanical behavior of the functionally gradient DLC films.

scholarly journals The Database Solution to Particle-by-Particle Analysis of Mixed Mineral Dusts

2007 ◽  
Vol 15 (6) ◽  
pp. 44-47 ◽  
Author(s):  
B.R. Strohmeier ◽  
K.L. Bunker ◽  
K.E. Harris ◽  
R. Hoch ◽  
R.J. Lee
Keyword(s):  
Electron Microscopy ◽  
Asbestos Exposure ◽  
Chemical Characterization ◽  
Particle Analysis ◽  
Particle Characterization ◽  
Public Attention ◽  
Transmission Electron ◽  
Mineral Dusts ◽  
Amphibole Asbestos

This work involves the development and application of a database for the morphological, crystallographic, and chemical characterization of amphibole particles that occur as accessory minerals in the former vermiculite mine in Libby, Montana. The data in the database were collected using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) techniques for particle-by-particle characterization of mixed mineral dust samples.In the fall of 1999, public attention was focused on the small town of Libby due to health concerns over potential amphibole asbestos exposure that occurred in the now closed vermiculite mine. The vermiculite deposit, located in the Rainy Creek Igneous Complex, about seven miles northeast of Libby, was discovered in 1913 and commercial production of vermiculite began in 1923.

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