Characterization of materials

Impedance Spectroscopy, Second Edition, edited by Evgenij Barsoukov and J. Ross Macdonald ISBN 0-471-64749-7 Copyright 2005 by John Wiley Sons, Inc. 

The electrical properties of heterogeneous media have been modeled for over 100 years. Meredith and Tobias [1962], Mitoff [1968], and McLachlan et al. [1990] have given clear accounts of their scope and vahdity. However, since these articles cover the case where the conductivity or permittivity are real, which normally means dc conductivity or permittivity of loss-free dielectrics, they are not directly apphca-ble to IS. AC properties have been discussed by Wimmer, Graham, and Tallan [1974] with special reference to ceramics. The dielectric literature has been reviewed by van Beek [1965], while Dukhin and Shilov [1974] have described models that include the effects of the interfacial double layer. Sihvola [1999] has produced a comprehensive survey of the properties of mixed phase systems with coverage of the historical and theoretical background. 

As this section emphasizes materials properties, the results are presented in terms of bulk intensive quantities, such as the complex conductivity the complex resistivity p, the permittivity e, and the modulus M. A distinction is made between two kinds of properties, both bulk intensive (i) macroscopic properties, such as the resistivity of a sample due to grain boundaries (after correction for length/area), which are directly measurable, and (ii) miaoscopic properties, such as the resistivity of the grain boundary phase, which can only be estimated with the help of a microstmctural model. The macroscopic quantities are represented by Latin symbols and the microscopic ones by Greek symbols. 

The quantity used for expressing models of this type is the complex conductivity, defined as 

The impedance and modulus spectra for this model in general consist of two semicircles. The diameters of these are gf. gi in the impedance and cf , c in the modulus spectra. The time constants of the two phases are defined as Ti = Ci/gi and 2 = C2/g2. If these time constants differ as a result of differences in c, then the arcs will be well resolved in the impedance spectrum. If they differ as a result of g, they will be resolved in the modulus spectrum (Hodge et al. [1976]). In practice, good resolution is not obtained in both Z and M spectra. 

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Migoun N.P. Proceedings of 7 Int. Symp. On Nondestructive Characterization of Materials. Material Science Forum, 1996, v.210-213, part 1, p. 387-388. 

Raman Microspectroscopy. Raman spectra of small soflds or small regions of soflds can be obtained at a spatial resolution of about 1 p.m usiag a Raman microprobe. A widespread appHcation is ia the characterization of materials. For example, the Raman microprobe is used to measure lattice strain ia semiconductors (30) and polymers (31,32), and to identify graphitic regions ia diamond films (33). The microprobe has long been employed to identify fluid iaclusions ia minerals (34), and is iacreasiagly popular for identification of iaclusions ia glass (qv) (35). 

The sputtering process is frequendy used in both the processing (e.g., ion etching) and characterization of materials. Many materials develop nonuniformities, such as cones and ridges, under ion bombardment. Polycrystalline materials, in particular, have grains and grain boundaries that can sputter at different rates. Impurities can also influence the formation of surface topography. ... 

For shock-synthesis and processing experiments, less precise systems are typically employed. These systems use commercial explosives that may be used to accelerate plates or to compress samples in the form of a tube. These systems are suitable for establishing nominal shock conditions for materials processing experiments, but are generally not suitable for careful characterization of materials response [87G02, 88M01]. 

Characterization of Materials by use of Electron Microscopy and Spectroscopy , General Electric Co (1971) 46) Anon, The National Frag ... 

After the verification of homogeneity and stability, the characterization of material can take place. Frequently, this step is named certification rather than characterization, which is wrong in view of the discussion about homogeneity and stability and their impact on the reference material. The certification of our reference material is more than the characterization of the material. Flowever, for most people working on the development of measurement methods, the characterization is the most interesting part of the project. This probably explains the huge amount of literature available. 

G. A. Matzkanin 1998, (A review of nondestructive characterization of composites using NMR) in Nondestructive Characterization of Materials, Springer, Berlin, pp. 655. 

Hutter H, Brunner C, Nikolov SG, Mittermayr C, Grasserbauer M (1996) Image surface spectroscopy for two and three dimensional characterization of materials. Fresenius J Anal Chem 355 585... 

Byrappa, K. and Adschiri, T. (2007) Hydrothermal technology for nanotechnology. Progress in Crystal Growth and Characterization of Materials, 53, 117-166. 

L. Mandelkern, Morphology of semicrystalline polymers. In Characterization of Materials Research Ceramics and Polymers, Syracuse University Press, 1975, p. 369. 

There has been substantial interest in the preparation and characterization of materials consisting of particles with dimensions in the order of 2-100 nm, so-called nanocrystalline materials. 336-343 One factor driving interest in nanoparticle research is the perceived need for the further miniaturization of... 

In the pharmaceutical industry, surface area is becoming more important in the characterization of materials during development, formulation, and manufacturing. The surface area of a solid material provides information about the void spaces on the surfaces of individual particles or aggregates of particles [5], This becomes important because factors such as chemical activity, adsorption, dissolution, and bioavailability of the drug may depend on the surface on the solid [3,5]. Handling properties of materials, such as flowability of a powder, can also be related to particle size and surface area [4],... 

Development Chemistry— Characterization of materials Characterization of process alternatives Choice of process Suitability of process Screening for chemical reaction hazards... 

However, for most studies, DTA has been mostly used in a qualitative sense as a means to determine the characteristic temperatures of thermally induced reactions. Owing to the experimental conditions used for its measurement, the technique is most useful for the characterization of materials that evolve corrosive gases during the heating process. The technique has been found to be highly useful as a means for compound identification based on the melting point considerations, and has been successfully used in the study of mixtures. 

Atomic force microscopy (AFM) is a commonly employed imaging technique for the characterization of the topography of material surfaces. In contrast to other microscopy techniques (e.g., scanning electron microscopy), AFM provides additional quantitative surface depth information and therefore yields a 3D profile of the material surface. AFM is routinely applied for the nanoscale surface characterization of materials and has been previously applied to determine surface heterogeneity of alkylsilane thin films prepared on planar surfaces [74,75,138]. 

F. Phillipp in Proc. of the Asian Science Seminar on New Directions in Transmission Electron Microscopy and Nano-Characterization of Materials, eds. C. Kinoshita, Y. Tomokiyo, and S. Matsumura (Kyushu University Press, Fukuoka, 1SBN4-87378-558-8) (1998) 75... 

E. Rhodes, C. E. Dickerman, C. W. Peters, Associated-Particle Sealed-Tube Neutron Probe for Characterization of Materials, ANL/B-E/CP-78949, Active Probe Technologies Conference on International Symposium on Substance Identification Technologies, 4—8 October 1993, Innsbruck, Austria. 

The University of Patras works on design and synthesis of materials, characterization of materials, catalyst development and evaluation, advanced electrochemical reactors, SOFCs, electrodes, and the reforming of fuels. 

A basic, yet crucially important, application of powder XRD is in the identification ( fingerprinting ) of crystalline phases, based on the fact that different crystal structures give rise to distinct powder XRD patterns. Qualitative characterization of materials in this manner finds applications in many scientific disciplines (both academic and industrial), including quality control, polymorph screening, and the characterization of products from rapid throughput crystallization experiments [97, 98]. 

William T. Heller obtained his PhD in physics from Rice University in 1999. After postdoctoral training at Los Alamos National Laboratory, he moved to Oak Ridge National Laboratory for additional postdoctoral training before accepting a post as chemist/biophysicist in the Chemical Sciences Division of Oak Ridge National Laboratory. His work entails the application of neutron and x-ray scattering methods to the study of the structure and function of biological macromolecules and the characterization of materials. 

The Rheometric Scientific RDAII dynamic analyzer is designed for characterization of polymer melts and solids in the form of rectangular bars. It makes computer-controlled measurements of dynamic shear viscosity, elastic modulus, loss modulus, tan 8, and linear thermal expansion coefficient over a temperature range of ambient to 600°C (—150°C optional) at frequencies 10-5 —500 rad/s. It is particularly useful for the characterization of materials that experience considerable changes in properties because of thermal transitions or chemical reactions. 

After a critical examination of the text, some material that has lost significance has been removed. A certain amount of new material, mainly components that have influenced modern fragrance trends over the past few years, have been added. The literature references in the chapter on Natural Raw Materials have been updated and the newest international standards for the characterization of materials have been included. 

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