Ferrites hexagonal, structure

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 ... 

The family of structurally related hexagonal ferrites contain intergrowths of these elemental building blocks S, R and T. 

Another hexagonal ferrite of interest is KFenOn, which has a structure similar to that of magnetoplumbite except for the FeBa03 layers, which are replaced by KO layers, see Fig. 15. 

The ferrites generally have one of three crystal structures inverse spinel, gameL and hexagonal. The spinel structures (cf. 

The hexagonal ferrites have a structure related to the spinel structure but with hexagonal close-packed oxygen ions and a unit cell made up of two formulae of MN12O19, where M is divalent (Ba, Sr, or Pb) and N is trivalent (Al, Ga, Cr, or Fe),... 

The structure of so-called hexagonal ferrite is based on the spinel (MgAljOJ structure. Arrangement of oxygen in spinel is CCP, and Mg and... 

Ferrites can he classified according lo eryslul structure, i.e., cubic vs hexagonal, or magnetic behavior, i.e, soft vs hard ferrites. 

Hexagonal ferrites crystallizing in the magnetoplumbite (PbFei2- Oi9) structure with the general chemical composition M Fe 2- 0 9. 

The magnetic properties of these compounds and hence their applications are closely coupled to their crystal structure. This is the basis of their classification into ferrites with soft magnetic properties (cubic) and hard magnetic properties (hexagonal). 

Although most materials grown by LPE have the garnet structure, spinel ferrites can be grown similarly, and films of hexagonal ferrites are also prepared ". Only small quantities are required, and the crystallographic quality of the film can be high, but a suitable substrate is required and the measurement or device must be made on a thin layer rather than a bulk crystal. 

Fundamental Properties of Hexagonal Ferrites with Magnetoplumbite Structure, by H. Kojima 305... 

Magnetic ceramics are further classified according to their crystal structures into spinels, garnets, and hexagonal ferrites. Typical compositions and some of their magnetic properties are listed in Table 15.4. 

The crystallographic structure of hard ferrites is such that the magnetically preferred (i.e., easy) orientation is the c axis, i.e., perpendicular to the basal plane. Consequently, hexagonal ferrites have been further classified as being either isotropic or anisotropic depending on whether the grains... 

Magnetic ceramics are ferrimagnetic and are classified according to their crystal structure into spinels, hexagonal ferrites, and garnets. 

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