Texture magnetic

Bentivegna, F. et al (1998) Magnetically textured y-Fe203 nanoparticles in a silica gel matrix structural and magnetic properties. /. Appl Phys., 83 (12), 7776-7788. 

R. (1999) Magnetically textured gamma-Fe20s nanoparticles in a silica gel matrix optical and magneto-optical properties. /. Appl. Phys., 85, 2270-2278. 

Coercivity of Thin-Film Media. The coercivity ia a magnetic material is an important parameter for appHcations but it is difficult to understand its physical background. It can be varied from nearly zero to more than 2000 kA/m ia a variety of materials. For thin-film recording media, values of more than 250 kA / m have been reported. First of all the coercivity is an extrinsic parameter and is strongly iafluenced by the microstmctural properties of the layer such as crystal size and shape, composition, and texture. These properties are directly related to the preparation conditions. Material choice and chemical inborn ogeneties are responsible for the Af of a material and this is also an influencing parameter of the final In crystalline material, the crystalline anisotropy field plays an important role. It is difficult to discriminate between all these parameters and to understand the coercivity origin ia the different thin-film materials ia detail. 

Oriented In-Plane Texture. In this kind of film the properties (H and in the various in-plane directions (texture and nontexture directions) are different. The texture of the film can be supported by the texture of the substrate and the crystal lattice can be smaller in the texture direction than in the transverse direction. This can be the source for strain-induced magnetic anisotropy (magnetostriction). It is also found that the crystal is aligned in the texture direction (92). 

Hot pressing to produce substantial texture and magnetic anisotropy via plastic deformation is accompHshed by a process referred to as... 

Selenium is added up to 0.1% to silicon steels (2—4% Si) used in transformer cores to enhance the development of the secondary recrystallization texture which, in turn, improves the magnetic characteristics. Selenium alloying additions to the melt may be made as elemental Se, nickel—selenium, or ferroselenium. The recovery depends on the melting practice and method of addition. Normally, it is in the range of 66%, but may be as high as 90%. 

Adapted from Guidotti et al. (189). Reaction conditions catalyst, 50 mg substrate, 1 mmol TBHP terpene (mol) =1 1 solvent, CH3CN Vtot mix., 10 mL temperature, 363 K time, 24 h magnetic stirring (ca. 800 rpm). Textural properties of the catalysts (A-E) are given in Table XII. Structures of the substrates (1-6) are shown in Scheme 6. 

A researcher in the field of heterogeneous catalysis, alongside the important studies of catalysts chemical properties (i.e., properties at a molecular level), inevitably encounters problems determining the catalyst structure at a supramolecular (textural) level. A powerful combination of physical and chemical methods (numerous variants x-ray diffraction (XRD), IR, nuclear magnetic resonance (NMR), XPS, EXAFS, ESR, Raman of Moessbauer spectroscopy, etc. and achievements of modem analytical chemistry) may be used to study the catalysts chemical and phase molecular structure. At the same time, characterizations of texture as a fairytale Cinderella fulfill the routine and very frequently senseless work, usually limited (obviously in our modem transcription) with electron microscopy, formal estimation of a surface area by a BET method, and eventually with porosimetry without any thorough insight. 

Texture has a rather marked influence on the properties of a given deposit. Thus, rather seemingly umelated parameters (properties), such as corrosion resistance, hardness, magnetic properties, porosity, contact resistance, and many others, are all texture dependent. By way of illustration, we discuss (6) first the case of magnetic properties. 

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