Special magnetic materials and applications

In this section, a short overview of magnetic materials in an early stage of development and of novel analysis techniques involving magnetic materials is given. It provides a picture of the exciting diversity of magnetic materials. 

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If the mesogens are pendant to the polymer backbone, materials are obtained with special magnetic, electrical and optical properties. They provide for nonlinear optics (NLOs) applications in numerous optoelectronic elements. 

In general, dw is written in the form (intensive variable)-d(extensive variable) or as a product of a force times a displacement of some kind. Several types of work terms may be involved in a single thermodynamic system, and electrical, mechanical, magnetic and gravitational fields are of special importance in certain applications of materials. A number of types of work that may be involved in a thermodynamic system are summed up in Table 1.1. The last column gives the form of work in the equation for the internal energy. 

Mixed-valence compounds continue to attract attention, not least because of their occurrence as intermediates of multistep redox systems Mixed-valence species are found in the geo- and biosphere, as evident from minerals such as Fe304 and from metalloproteins, where the Fe /Fe °/Fe, Cu /Cu and Mn / Mn Nn combinations are established Man-made mixed-valence compounds, starting from Prussian Blue in the early 18th century, have raised interest in what is now known as materials science because of their often special optical, electrical and magnetic properties These physical properties then prompted attempts at increasingly sophisticated levels to theoretically understand and computationally reproduce the experimental features of mixed-valence compounds More recent developments involve the application of mixed-valence systems as models and actual components in the areas of molecular electronics and molecular computing ... 

Intermetallics were used in this century first and primarily for applications as functional materials, as is exemplified in Table 1. Indeed the first industrial applications relied on the special magnetic behavior of certain phases, and respective materials developments led e.g. to Sendust, which shows outstanding magnetic properties and wear resistance and is widely used for magnetic heads in tape recorders (Yamamoto, 1980 Brock, 1986). In the second... 

Ordered (and partially ordered) arrays of metal sites and complexes enable the cooperation of their special electronic, magnetic and optical properties. Such materials have long been sought for their expected physical properties and applications in optics, electrooptics, superconductivity and sensors. The ordering can be by various mechanisms, such as adsorption on surfaces, intercalation into layered structures, formation of mesomorphic structures and liquid crystals, and adoption of specific crystal-packing motifs, all of which are supramolecular phenomena. Organic liquid crystals and their applications are now commonplace, and in recent years the incorporation of metal atoms into mesogenic molecules has demonstrated the occurrence of similar metallo-mesophases [20]. 

In the nanotechnology field, carbon-based materials and associated composites have received special attention both for fundamental and applicative research. In the first kind, carbon compounds may be included, often taking the form of a hollow spheres, ellipsoids, or mbes. Spherical and ellipsoidal carbon nanomaterials are referred to as fullerenes, while cylindrical ones are called nanombes and nanofibers. In the second class, one includes composite materials that combine carbon nanoparticles with other nanoparticles, or nanoparticles with large bulk-type materials. The unique properties of these various types of nanomaterials provide novel electrical, catalytic, magnetic, mechanical, thermal, and other features that are desirable for applications in commercial, medical, military, and enviromnental sectors. This is the case for conducting polymers (CPs) and carbon nanombes (CNTs) [1-5]. 

Among aU kinds of nanomaterials, magnetic nanoparticles earn their position by their special features and widely used applications. Compared to regular magnetic materials, nanoparticles differ from the domain stmcture to the classic quantum... 

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