Properties of Individual Particles

2007 ◽  
pp. 119-182
Keyword(s):  
Author(s):  
Gregory L. Finch ◽  
Richard G. Cuddihy

The elemental composition of individual particles is commonly measured by using energydispersive spectroscopic microanalysis (EDS) of samples excited with electron beam irradiation. Similarly, several investigators have characterized particles by using external monochromatic X-irradiation rather than electrons. However, there is little available information describing measurements of particulate characteristic X rays produced not from external sources of radiation, but rather from internal radiation contained within the particle itself. Here, we describe the low-energy (< 20 KeV) characteristic X-ray spectra produced by internal radiation self-excitation of two general types of particulate samples; individual radioactive particles produced during the Chernobyl nuclear reactor accident and radioactive fused aluminosilicate particles (FAP). In addition, we compare these spectra with those generated by conventional EDS.Approximately thirty radioactive particle samples from the Chernobyl accident were on a sample of wood that was near the reactor when the accident occurred. Individual particles still on the wood were microdissected from the bulk matrix after bulk autoradiography.


Author(s):  
JR Fryer ◽  
Z Huang ◽  
D Stirling ◽  
G. Webb

Platinum dispersed on γ-alumina is used as a reforming catalyst to convert linear hydrocarbons to cyclic aromatic products. To improve selectivity and lifetime of the catalyst, other elements are included, and we have studied the distributions of Pt/Re, and Pt/Sn, bimetallic systems on the support both before and after use in octane reforming. Often, one or both of the components are not resolvable by HREM or microanalysis as individual particles because of small size and lack of contrast on the alumina, and divergent beam microanalysis has been used to establish the presence and relationship between the two elements.In the majority of catalysts the platinum is in the form of small panicles, some of which are large enough to be resolvable in the microscope. The ABT002B microscope with Link windowless Pentafet detector, used in this work, was able to obtain a resolvable signal from particles of 2nm diameter upwards. When the beam was concentrated on to such a particle the signal was at a maximum, and as the beam diameter was diverged - at the same total beam intensity and dead time - the signal decreased as shown in Figure 1.


Author(s):  
M. L. Scriabin ◽  
A. I. Chuprakov

The paper deals with the classification of defects of castings obtained by electric arc smelting. Of particular interest to researchers is the rock-like and naphthalene fracture, but there is still no clear mechanism explaining its origin. A stone-like fracture is characterized by a clearly defined uniform surface over which the fracture occurs. Grain boundaries are partially soluble in the austenite phase, consisting of fine individual particles or films formed from molten eutectics. It is also worth noting that in most cases, the stone-like fracture is observed at the grain boundaries.


Author(s):  
Denisa Olekšáková ◽  
Peter Kollár ◽  
Miloš Jakubčin ◽  
Ján Füzer ◽  
Martin Tkáč ◽  
...  

AbstractThis submitted paper presents the detailed description of the energy loss separation for dc and ac low-frequency magnetic fields of NiFeMo (supermalloy) compacted powder prepared by innovative method of smoothing the surfaces of individual particles. The positive impact of mechanical treatment method on domain wall displacement is explained on the basis of Landgraf approach for dc loss analysis, and the effective dimension for eddy current in ac magnetic field is explained according to Bertotti approach for core loss analysis.


2001 ◽  
Vol 32 ◽  
pp. 683-684
Author(s):  
M. EBERT ◽  
S. WEINBRUCH ◽  
A. RAUSCH ◽  
G. GORZAWSKI ◽  
H. WEX ◽  
...  

2021 ◽  
Vol 7 (20) ◽  
pp. eabe3392
Author(s):  
Erin G. Teich ◽  
K. Lawrence Galloway ◽  
Paulo E. Arratia ◽  
Danielle S. Bassett

The nature of yield in amorphous materials under stress has yet to be fully elucidated. In particular, understanding how microscopic rearrangement gives rise to macroscopic structural and rheological signatures in disordered systems is vital for the prediction and characterization of yield and the study of how memory is stored in disordered materials. Here, we investigate the evolution of local structural homogeneity on an individual particle level in amorphous jammed two-dimensional (athermal) systems under oscillatory shear and relate this evolution to rearrangement, memory, and macroscale rheological measurements. We define the structural metric crystalline shielding, and show that it is predictive of rearrangement propensity and structural volatility of individual particles under shear. We use this metric to identify localized regions of the system in which the material’s memory of its preparation is preserved. Our results contribute to a growing understanding of how local structure relates to dynamic response and memory in disordered systems.


2012 ◽  
Vol 31 (2) ◽  
pp. 65 ◽  
Author(s):  
Eric Pirard

In recent years, impressive progress has been made in digital imaging and in particular in three dimensional visualisation and analysis of objects. This paper reviews the most recent literature on three dimensional imaging with a special attention to particulate systems analysis. After an introduction recalling some important concepts in spatial sampling and digital imaging, the paper reviews a series of techniques with a clear distinction between the surfometric and volumetric principles. The literature review is as broad as possible covering materials science as well as biology while keeping an eye on emerging technologies in optics and physics. The paper should be of interest to any scientist trying to picture particles in 3D with the best possible resolution for accurate size and shape estimation. Though techniques are adequate for nanoscopic and microscopic particles, no special size limit has been considered while compiling the review.


2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Ling Sun ◽  
Jianjun Wang ◽  
Elmar Bonaccurso

2005 ◽  
Vol 11 (4) ◽  
pp. 354-362 ◽  
Author(s):  
Uri Admon ◽  
David Donohue ◽  
Helmut Aigner ◽  
Gabriele Tamborini ◽  
Olivier Bildstein ◽  
...  

Physical, chemical, and isotopic analyses of individual radioactive and other particles in the micron-size range, key tools in environmental research and in nuclear forensics, require the ability to precisely relocate particles of interest (POIs) in the secondary ion mass spectrometer (SIMS) or in another instrument, after having been located, identified, and characterized in the scanning electron microscope (SEM). This article describes the implementation, testing, and evaluation of the triangulation POIs re-location method, based on microscopic reference marks imprinted on or attached to the sample holder, serving as an inherent coordinate system. In SEM-to-SEM and SEM-to-SIMS experiments re-location precision better than 10 μm and 20 μm, respectively, is readily attainable for instruments using standard specimen stages. The method is fast, easy to apply, and facilitates repeated analyses of individual particles in different instruments and laboratories.


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