Cryomicroscopy of multiphase latices

1991 ◽  
Vol 49 ◽  
pp. 1060-1061
Author(s):  
O. L. Shaffer ◽  
M.S. El-Aasser ◽  
C. L. Zhao ◽  
M. A. Winnik ◽  
R. R. Shivers
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Freeze Fracture ◽  
Particle Morphology ◽  
Second Stage ◽  
Transmission Electron ◽  
Important Approach ◽  
Carbon Coated ◽  
Preparation Techniques

Transmission electron microscopy is an important approach to the characterization of the morphology of multiphase latices. Various sample preparation techniques have been applied to multiphase latices such as OsO4, RuO4 and CsOH stains to distinguish the polymer phases or domains. Radiation damage by an electron beam of latices imbedded in ice has also been used as a technique to study particle morphology. Further studies have been developed in the use of freeze-fracture and the effect of differential radiation damage at liquid nitrogen temperatures of the latex particles embedded in ice and not embedded.Two different series of two-stage latices were prepared with (1) a poly(methyl methacrylate) (PMMA) seed and poly(styrene) (PS) second stage; (2) a PS seed and PMMA second stage. Both series have varying amounts of second-stage monomer which was added to the seed latex semicontinuously. A drop of diluted latex was placed on a 200-mesh Formvar-carbon coated copper grid.

Nanostructured oxides for energy storage applications in batteries and supercapacitors

2009 ◽  
Vol 81 (8) ◽  
pp. 1489-1498 ◽  
Author(s):  
Amreesh Chandra ◽  
Alexander J. Roberts ◽  
Eric Lam How Yee ◽  
Robert C. T. Slade
Keyword(s):  
Electron Microscopy ◽  
Energy Storage ◽  
Specific Capacitance ◽  
Electrode Materials ◽  
Particle Morphology ◽  
Hydrothermal Route ◽  
Conductivity Enhancement ◽  
Surface Areas ◽  
Transmission Electron

Nanostructured materials are extensively investigated for application in energy storage and power generation devices. This paper deals with the synthesis and characterization of nanomaterials based on oxides of vanadium and with their application as electrode materials for energy storage systems viz. supercapacitors. These nano-oxides have been synthesized using a hydrothermal route in the presence of templates: 1-hexadecylamine, Tweens and Brij types. Using templates during synthesis enables tailoring of the particle morphology and physical characteristics of synthesized powders. Broad X-ray diffraction peaks show the formation of nanoparticles, confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations. SEM studies show that a large range of nanostructures such as needles, fibers, particles, etc. can be synthesized. These particles have varying surface areas and electrical conductivity. Enhancement of surface area as much as seven times relative to surface areas of starting parent materials has been observed. These properties make such materials ideal candidates for application as electrode materials in supercapacitors. Assembly and characterization of supercapacitors based on electrodes containing these active nano-oxides are discussed. Specific capacitance of >100 F g–1 has been observed. The specific capacitance decreases with cycling: causes of this phenomenon are presented.

scholarly journals Characterization of Carbon-Coated Titania Nanoparticles with Transmission Electron Microscopy

2013 ◽  
Vol 19 (S2) ◽  
pp. 1546-1547
Author(s):  
D.H. Anjum ◽  
N. Memon ◽  
S.H. Chung
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Titania Nanoparticles ◽  
Transmission Electron ◽  
Carbon Coated

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Improving transmission electron microscopy characterization of semiconductors by minimizing sample preparation artifacts

1992 ◽  
Vol 70 (10-11) ◽  
pp. 875-880 ◽  
Author(s):  
J. P. McCaffrey ◽  
G. I. Sproule ◽  
R. Sargent
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Ion Milling ◽  
Transmission Electron ◽  
Transmission Electron Microscopy Characterization ◽  
Silicon Based ◽  
Microscopy Characterization ◽  
Preparation Techniques

Techniques employed for the preparation of transmission electron microscopy (TEM) samples can introduce artifacts that obscure subtle detail in the materials being studied. Traditional semiconductor sample preparation techniques rely heavily on ion milling, which leaves amorphous layers on ion milled surfaces and some intermixing across interfaces, thus degrading the TEM images of these samples. Experimental results of the extent of this amorphization and intermixing are presented for silicon-based semiconductor samples, and methods to minimize these effects are suggested. These methods include variations in ion milling parameters that reduce the extent of the artifacts, and improvements in the small-angle cleavage technique that eliminate these artifacts completely.

scholarly journals TEM Sample Preparation: An Interdisciplinary Website

2009 ◽  
Vol 17 (2) ◽  
pp. 38-41 ◽  
Author(s):  
Jeanne Ayache ◽  
Luc Beaunier ◽  
Jacqueline Boumendil ◽  
Gabrielle Ehret ◽  
Danièle Laub
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Material Science ◽  
International Community ◽  
Central Importance ◽  
Transmission Electron ◽  
Characterization Of Materials ◽  
Preparation Techniques

Sample preparation is of central importance for the characterization of materials by transmission electron microscopy (TEM). As a guide to researchers seeking practical help on the use of all types of TEM sample preparation techniques, we have created an Internet website. This website has been designed in French and is now translated into English. The website is accessible free of charge.The TEMSAMPREP website, figure 1 http://temsamprep.in2p3.fr/, is the result of a synergistic effort of an atypical team of five electron microscopy scientists having different research specialties in physics, mineralogy, material science, and biology. They shared five years of human adventure in creating the website to transmit their 30 years of TEM experience to the international community.

Cryomicroscopy of low-Tg latex particles via freeze drying

1993 ◽  
Vol 51 ◽  
pp. 1198-1199
Author(s):  
J. R. Reffner
Keyword(s):  
Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Film Formation ◽  
Direct Determination ◽  
Particle Morphology ◽  
Latex Particles ◽  
Transmission Electron

Transmission Electron Microscopy (TEM) is a powerful tool for investigating the structure of latex particles. However, examining low Tg (glass transision, Tg < room temperature) latex particles requires special techniques due to the significant deformation which occurs if the particles are dispersed onto a substrate at room temperature. Here a freeze drying (FD) technique is presented which permits individual emulsion particles, including stained particles, to be examined in a manner that minimizes deformation by maintaining the particles at temperatures below Tg.Typically, particle morphology is determined from images of individual latex particles dispersed onto a supporting ultra-thin substrate or from images of ultra-microtomed sections of films cast from the latex. Examining particles dispersed onto a substrate is often advantageous, allowing direct determination of particle shape and characterization of the morphology prior to the film formation process. Although low Tg materials can be examined using this technique, information about the size, shape and morphology of phase separated domains can be obscured by the deformation which occurs when the particles are examined at room temperature.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

1968 ◽  
Vol 26 ◽  
pp. 442-443 ◽  
Author(s):  
L.E. Murr ◽  
A.B. Draper
Keyword(s):  
Electron Microscopy ◽  
State Physics ◽  
Test Material ◽  
Milling Machine ◽  
Rotary Table ◽  
Solid State Physics ◽  
Materials Properties ◽  
Transmission Electron ◽  
Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

Interface structures in polycrystalline ceramic materials

1986 ◽  
Vol 44 ◽  
pp. 468-471
Author(s):  
K. J. Morrissey
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Physical And Mechanical Properties ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Polycrystalline Materials ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Interface Structures

Grain boundaries and interfaces play an important role in determining both physical and mechanical properties of polycrystalline materials. To understand how the structure of interfaces can be controlled to optimize properties, it is necessary to understand and be able to predict their crystal chemistry. Transmission electron microscopy (TEM), analytical electron microscopy (AEM,), and high resolution electron microscopy (HREM) are essential tools for the characterization of the different types of interfaces which exist in ceramic systems. The purpose of this paper is to illustrate some specific areas in which understanding interface structure is important. Interfaces in sintered bodies, materials produced through phase transformation and electronic packaging are discussed.

Sign in / Sign up

Export Citation Format

Share Document