Microbeam analysis. Analytical electron microscopy. Selected-area electron diffraction analysis using a transmission electron microscope

Automotive catalysts have a general loss of activity during aging, basically due to two principal deactivation mechanisms. One of them is thermally induced “sintering,” which results in catalytic surface area reduction. The other is chemically induced “poisoning,” which in part causes blockage of active metal sites. The conventional bulk techniques have indicated that various catalyst functions were affected differently by poisons and thermal damage; however, they generally did not provide detailed descriptions of the mechanisms of deactivation. Only analytical electron microscopy (AEM) can provide microchemical and microstructural information to gain a more thorough and fundamental understanding of catalytic deactivation.Fresh and vehicle-aged commercial automotive catalysts containing Pt, Pd, and Rh on alumina supports were prepared for AEM by a microtomy technique, which retains the spatial integrity of the catalyst pellet with uniform thickness. Then these AEM specimens were characterized in a transmission electron microscope (TEM) and in a dedicated scanning transmission electron microscope (STEM).

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Electron Diffraction Analysis and Determination of Se Phase Formed by Reduction of Oxoselenium Anions by Iron (II) Hydroxide

Microscopy and Microanalysis ◽

10.1017/s1431927600010667 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 755-756

Author(s):

D. C. Dufner ◽

R. A. Zingaro ◽

A. P. Murphy ◽

C. D. Moody

Keyword(s):

Aqueous Solution ◽

Electron Microscope ◽

Electron Diffraction ◽

Transmission Electron Microscope ◽

Iron Hydroxide ◽

Distilled Water ◽

Electron Diffraction Analysis ◽

Transmission Electron ◽

Standard Solution

Since the early 1980s, Se toxicity in wildlife has created a great deal of interest and concern. Reservoirs, marshes, and wetlands in which excessive amounts of Se have been found are considered to be the source of their toxicity problems. Thus, an effective and inexpensive treatment of Se-contaminated waters which significantly lowers the concentration of this element is needed. One such method for removing selenites and selenates from water utilizes iron (II) hydroxide as a reducing agent. In this work, the reduction products are analyzed in the transmission electron microscope (TEM) using electron diffraction and energy-dispersive spectroscopy (EDS) to determine the presence of Se.A “standard” aqueous solution was prepared by the addition of KOH to distilled water to pH 8.8. Sufficient quantities of Na2SeO3 or Na2SeO4 were weighed and dissolved in the “standard” solution to yield SeO3-2 or SeO4-2 ions. A weighed quantity of Fe(NH4)2(SO4)2 was then added to the SeO3-2 or SeO4-2 “standard” solution to form a precipitate of iron hydroxide.

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Magnetite exsolution in almandine garnet

Mineralogical Magazine ◽

10.1180/minmag.1986.050.358.07 ◽

1986 ◽

Vol 50 (358) ◽

pp. 621-633 ◽

Cited By ~ 13

Author(s):

A. J. Brearley ◽

P. E. Champness

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Electron Microprobe ◽

Microprobe Analysis ◽

Electron Microprobe Analysis ◽

Spinel Phase ◽

Analytical Electron Microscopy ◽

Transmission Electron ◽

Analytical Electron ◽

Rare Situation

AbstractThree almandine-rich metamorphic garnets have been studied by analytical electron microscopy and electron microprobe analysis. Electron microprobe analyses with total Fe calculated as Fe2+ show that there are no significant departures from stoichiometry due to the presence of Fe3+ in any of the garnets studied. However, in the transmission electron microscope (TEM) all the garnets were found to contain myriad spherical, iron-rich particles up to 400 Å in diameter. Microdiffraction techniques have revealed that the particles are a cubic spinel phase, consistent with magnetite. There is no crystallographic relationship between the host garnet and the particles, a rare situation for exsolution processes. The presence of such particles is interpreted in terms of the exsolution of magnetite from almandine garnet during cooling. This can apparently occur at temperatures below 55°C. The size of the particles is a qualitative indicator of the cooling rate of the rock, but is also dependent on the original Fe3+ content of the host garnet.

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Accurate and precise lattice parameters by selected-area electron diffraction in the transmission electron microscope

American Mineralogist ◽

10.2138/am.2009.2994 ◽

2009 ◽

Vol 94 (5-6) ◽

pp. 793-800 ◽

Cited By ~ 21

Author(s):

E. Mugnaioli ◽

G. Capitani ◽

F. Nieto ◽

M. Mellini

Keyword(s):

Electron Microscope ◽

Electron Diffraction ◽

Transmission Electron Microscope ◽

Lattice Parameters ◽

Selected Area Electron Diffraction ◽

Transmission Electron

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The Formation and Utility of Sub-Angstrom to Nanometer-Sized Electron Probes in the Aberration-Corrected Transmission Electron Microscope at the University of Illinois

Microscopy and Microanalysis ◽

10.1017/s1431927610000085 ◽

2010 ◽

Vol 16 (2) ◽

pp. 183-193 ◽

Cited By ~ 25

Author(s):

Jianguo Wen ◽

James Mabon ◽

Changhui Lei ◽

Steve Burdin ◽

Ernie Sammann ◽

...

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Electron Diffraction ◽

Transmission Electron Microscope ◽

Spherical Aberration ◽

Real Space ◽

Dark Field ◽

Atomic Scale ◽

Transmission Electron ◽

Scanning Transmission

AbstractWe evaluate the probe forming capability of a JEOL 2200FS transmission electron microscope equipped with a spherical aberration (Cs) probe corrector. The achievement of a real space sub-Angstrom (0.1 nm) probe for scanning transmission electron microscopy (STEM) imaging is demonstrated by acquisition and modeling of high-angle annular dark-field STEM images. We show that by optimizing the illumination system, large probe currents and large collection angles for electron energy loss spectroscopy (EELS) can be combined to yield EELS fine structure data spatially resolved to the atomic scale. We demonstrate the probe forming flexibility provided by the additional lenses in the probe corrector in several ways, including the formation of nanometer-sized parallel beams for nanoarea electron diffraction, and the formation of focused probes for convergent beam electron diffraction with a range of convergence angles. The different probes that can be formed using the probe corrected STEM opens up new applications for electron microscopy and diffraction.

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Microcharacterization of Heterogeneous Specimens Containing Tire Dust

MRS Proceedings ◽

10.1557/proc-589-147 ◽

1999 ◽

Vol 589 ◽

Cited By ~ 1

Author(s):

Marina Camatini ◽

GAI M Corbetta ◽

Giovanini F Crosta ◽

Tigran Dolukhanyan ◽

Giampaolo Giuiani ◽

...

Keyword(s):

Electron Microscope ◽

Analytical Electron Microscopy ◽

X Ray ◽

Selected Area Electron Diffraction ◽

Transmission Electron ◽

Debris Particles ◽

Microscope Images ◽

Analytical Electron ◽

Diffraction Patterns

AbstractThis work is focused on dust or debris produced by the wear of tire tread. Two problems are addressed, which are solved by analytical electron microscopy (AEM): characterization of tire debris and identification of tire debris particles in a heterogeneous specimen. The characteristic morphology, microstructure and elemental composition of tire debris can all be determined by AEM. The scanning electron microscope (SEM) shows that the surface of a tire debris particle has a typical, warped structure with pores. The characteristic elements of tire rubber are S and Zn, which are detected by energy dispersive X ray (EDX) spectroscopy. The identification of rubber particles in heterogeneous debris containing talc and produced by a laboratory abrader is possible by the analytical SEM. Transmission electron microscope images, EDX spectra and selected area electron diffraction patterns characterize tire debris at the sub–micron scale, where the material can no longer be treated as homogeneous.

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