Magnetic materials hexagonal ferrites

Ferrites can be classified according to crystal stmcture, ie, cubic vs hexagonal, or magnetic behavior, ie, soft vs hard ferrites. A systematic classification as well as some appHcations ate given in Table 1 (see also Magnetic materials, bulk Magnetic materials, thin film). 

Albanese, G., Carbucicchio, M., Pared, L., Rinaldi, S., Licchini, E. Slokar, G. (1980). Magnetic and Mossbauer study of Al, Ga, In and Sc-substituted Zn2 W hexagonal ferrites. Journal of Magnetism and Magnetic Materials, 15-18, 1453. 

X-type hexagonal ferrites. Journal of Magnetism and Magnetic Materials, 31-34, 803-4. 

Samaras, D., Collomb, A., Hadjivasiliou, S., Achilleos, C, Tsoukalas, J., Pannetier, J. Rodriguez, J. (1989). The rotation of magnetization in the BaCojFeigOjT W-type hexagonal ferrites. Journal of Magnetism and Magnetic Materials, 79, 193-201. 

Hibst, H. (1982). Hexagonal ferrites from melts and aqueous solutions, magnetic recording materials. Angewande Chemie, International Edition in English, 21, 270-81. 

Lotgering, F. K., Vromans, P. H. G. M. Huyberts, M. A. H. (1980). Permanent-magnet material obtained by sintering the hexagonal ferrite W = BaFeig027. Journal of Applied Physics, 51, 5913-18. 

Hard magnetic materials have rather rectangular, broad, hysteresis curves (Figure 12.16). These materials are used in permanent magnets, with applications from door catches to electric motors. The hexagonal ferrites are hard magnetic materials, as are alloys such as SmCos and Nd2Fei4B. 

Estimate (a) the saturation magnetisation and (b) the magnetic inductance for the hexagonal ferrite ferroxdur , BaFei20i9. The hexagonal unit cell has parameters flo = 0.58836 nm, cq = 2.30376 nm and volume 7.128 x 10 m. There are two formula units in the unit cell. Assmne that the orbital angular momentum is completely quenched in this material. 

Soft ferrites and hard ferrites or hexaferrites are important materials for magnetic uses. Soft ferrites are crystals with a spinel structure whose reference is magnetite Fe304 hard hexaferrites are crystals with a hexagonal structure, whose type is BaFe 2 i9 ... 

Table 4.3-5< BaO—MeO—Fe203 hexagonal magnetic compounds and their technical designations as hard ferrite materials 3.10...

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