Magnetic spinel ferrite

The soft magnetic spinel ferrites, by far the most important cubic ferrites, were first introduced by Philips under the trade name Ferroxcube (14) and are now widely commercially available under various trade names. The world market for soft magnetic ferrites amounts to about one biUion dollars (1991), about 350 million dollars of which is in the United States. 

Soft magnetic spinel ferrites, 11 57 Soft oils, in toilet soap making, 22 734 Soft repulsions, 23 94 Soft rot... 

Table 33.10 compares some of the relevant properties of metal and ceramic soft magnets. Spinel ferrites based upon the (Mn,Zn,Fe)04 system are examples of commercially important soft magnets. The market for soft ferrites is about 50,0001 per year. These are usually marketed under the trade name Ferroxcube. 

Liu, C., Rondinone, A.J., Zhang, Z.J. Synthesis of magnetic spinel ferrite CoFc204 nanoparticles from ferric salt and characterization of the size-dependent superparamagnetic properties. Pure Appl. Chem. 72, 37-45 (2000)... 

C. Liu, A. J. Rondinone and Z. J. Zhang, Synthesis of magnetic spinel ferrite CoFe204 nanoparticles... 

Spinel ferrites, isostmctural with the mineral spinel [1302-67-6] MgAl204, combine interesting soft magnetic properties with a relatively high electrical resistivity. The latter permits low eddy current losses in a-c appHcations, and based on this feature spinel ferrites have largely replaced the iron-based core materials in the r-f range. The main representatives are MnZn-ferrites (frequencies up to about 1 MH2) and NiZn-ferrites (frequencies 1 MHz). 

An interesting study of oxidic spinel ferrites of the type CO cNi5/3 xFeSbi/304 was reported [21], where three different Mbssbauer-active probes Fe, Ni and Sb were employed on the same material. The results have been interpreted in terms of the cation distributions over spinel A- and B-lattice sites, magnetic moments and spin structure, and the magnitude of the supertransferred hyperfine... 

Vestal, C.R. and Zhang, Z.J. (2003) Synthesis and magnetic characterization of Mn and Co spinel ferrite—silica nanopartides with tunable magnetic core. Nano Letters, 3 (12), 1739-1743. 

The spinel ferrites were fabricated by solid state reaction technique. Cobalt and Zinc ferrites CoxZnyFe204,(x=0.7,0.3,0.4,0.2 and y=0.3,0.7,0.6,0.8) were prepared by solid state reaction technique. The crystalline structure of the sample was investigated by X-ray diffraction(XRD). All samples show cubic spinel structure. The lattice parameter decreases with increasing cobalt content. Magnetic properties shows that the prepared sample exhibit ferromagnetic behaviour at room temperature. The saturation magnetization increases with increasing cobalt content. Curie temperature... 

Mollard, P. Germi, P. Rousset, A. (1977) Surface effects of saturation magnetization of fine spinel ferrite particles. Physica 86-88 B-rC 1393-1394... 

Figure 1.41) have the oxygen ions in a nearly close-packed cubic array. The unit cell contains 32 oxygen ions, with 32 octahedral and 64 tetrahedral sites, of which 16 of the octahedral and 8 of the tetrahedral sites are filled. It is the position of these 24 cations within the unit cell that determines magnetic behavior. The distribution of cations in the sites is specific to the type of cations, and it must be determined experimentally. There are two idealized spinel structures. In the normal spinel, all the divalent ions are on the tetrahedral sites, as in ZnFe204. In the inverse spinel, the 8 occupied tetrahedral sites are filled with trivalent ions and the 16 occupied octahedral sites are equally divided between di- and trivalent ions (see Figure 6.63). The prototypical inverse spinel ferrite is magnetite, whose structure consists of an FCC oxygen array with Fe + and Fe + ions in the interstices.

Five aspects of the preparation of solids can be distinguished (i) preparation of a series of compounds in order to investigate a specific property, as exemplified by a series of perovskite oxides to examine their electrical properties or by a series of spinel ferrites to screen their magnetic properties (ii) preparation of unknown members of a structurally related class of solids to extend (or extrapolate) structure-property relations, as exemplified by the synthesis of layered chalcogenides and their intercalates or derivatives of TTF-TCNQ to study their superconductivity (iii) synthesis of a new class of compounds (e.g. sialons, (Si, Al)3(0, N)4, or doped polyacetylenes), with novel structural properties (iv) preparation of known solids of prescribed specifications (crystallinity, shape, purity, etc.) as in the case of crystals of Si, III-V compounds and... 

Generally speaking, the spinel ferrites have low magnetic anisotropies and are magnetically soft exceptions are those containing Co2+ which is itself strongly... 

Poster 33. Akira Kubo, Shinta Watanabe, Hiroki Moriwake and Kazuyoshi Ogasawara (Kwansei Gakuin University, Japan Fine Ceramics Center) An Approach for Design of Magnetic Materials Based on Spinel Ferrites using First-Principles Calculations... 

Most spinel ferrites used in device applications are not simple ternary oxides but rather contain proprietary mixtures of several different magnetic ions tailor made for specific applications. So-called (Mn, Zn) ferrites of general formula Zn+ c Fe+ i-x[Mn+ i cF ]04 and related (Ni, Zn) ferrites... 

Ayyappan S, Mahadevan S, Chandramohan P, Srinivasan MP, Philip J, Raj B (2010) Influence of Co ion concentration on the size, magnetic properties, and purity of CoFe204 spinel ferrite nanoparticles. J Phys Chem C 114 6334-6341... 

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