Chapter 5 Fundamental properties of hexagonal ferrites with magnetoplumbite structure

Kojima, Hiroshi

doi:10.1016/s1574-9304(05)80091-4

Cited by 188 publications

(59 citation statements)

References 142 publications

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“…The anisotropy constants K 1 of BaM and SrM ferrites are 3.3·10 6 and 3.6·10 6 erg/cm 3 respectively and the saturation magnetizations are 380 and 365 emu/cm 3 , respectively [7]. The structure of the hexaferrite is based on hexagonal lattice in which Fe 3+ ions are arranged in five kinds of sites: three are octahedral, one is tetrahedral and the last one is a site in which the Fe ion is surrounded by five oxygen atoms forming a trigonal bipyramid [8].…”

Section: Introductionmentioning

confidence: 99%

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Heat-treatment influence on the microstructure and magnetic properties of rare-earth substituted SrFe12O19

Doroftei

Rezlescu

Popa

et al. 2006

Cryst. Res. Technol.

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Rare-earth substituted strontium ferrite nanopowders SrFe 12-x R x O 19 (R = La, Gd and Er; x = 0.2, 0.5 and 1) were prepared by sol-gel-autocombustion method and subsequent heat treatments. Structural and magnetic properties of SrFe 12-x R x O 19 powders heat treated at 800, 900 and 1000 0 C, for various times, were characterized with an X-ray diffractometer, a vibrating sample magnetometer and a scanning electron microscope. The results of X-ray diffraction measurements showed the M-type hexagonal structure formation by heat treatments. Magnetic properties, such as specific saturation magnetization σ s , specific remanent magnetization σ r and coercivity H c , as well as microstructure depend on the heat treatment conditions (temperature and time). The coercivity H c exhibits a great increase after a critical heat treatment time. When the heat treatment time increases, one obtains an increase in H c after a shorter heat treatment time. This jump of H c was explained by a transition from the superparamagnetic state to normal state of the single domain nanoparticles. The occurrence of an agglomerated structure composed of magnetically interacting ultrafine crystallites also contributes to the increase of H c .The heat treatment determines a reduced grain growth due to the internal stress generated by R ions. With increasing R content the σ s and σ r decrease due to the dissolution of R ions into the hexaferrite lattice. We believe that by selecting the time and temperature of the heat treatment, microstructure and magnetic properties suitable for magnetic recording media application can be obtained.

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Section: Introductionmentioning

confidence: 99%

“…Most of the works on the hexagonal ferrites were focussed on BaM ferrites. Previously, Kojima [8] reported that the substitution of Ba 2+ by Sr 2+ in BaFe 12 O 19 has improved the magnetic properties. In the present paper we investigate the SrM ferrites containing three rare earth elements: La, Gd and Er.…”

Section: Introductionmentioning

confidence: 99%

Heat-treatment influence on the microstructure and magnetic properties of rare-earth substituted SrFe12O19

Doroftei

Rezlescu

Popa

et al. 2006

Cryst. Res. Technol.

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“…1-5 The significant properties of BaM ferrite are high magnetization, remanence, coercivity, electrical resistivity, and great resistance to corrosion. [1][2][3][4][5][6][7][8] Therefore, the progress of new and low cost effective technique for constructing structures based on BaM ferrite is one of great commercial and scientific interests.…”

Section: Introductionmentioning

confidence: 99%

Remarkable magnetic enhancement of type-M hexaferrite of barium in polystyrene polymer

et al. 2015

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We demonstrate that the promising effect of inclusion of single magnetic-domain type-M hexaferrite of barium (BaM) particles in polystyrene (PS) polymer (BaM/PS weight ratio = 2/1). The results show that the coercivity of BaM particles remarkably increases from 714 to 3772 Oe and remanence increases from 2.07 to 5.41 emu.g−1 when they embedded into PS. Moreover, magnetic coercivity and squareness of the BaM-PS are significantly larger, and is comparable with corresponding values of other BaM-polymer composites. Therefore, BaM-PS composite enforce itself as the modern potential materials with tendency of replacing existing composite materials in several applications.

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“…Hexagonal Ba-ferrites are widely suggested as materials for small antennas. [4]. Among these Baferrites, the Co 2 Z ferrite (Ba 3 Co 2 Fe 24 O 41 ) has a relatively high permeability and resonance frequency.…”

Section: Introductionmentioning

confidence: 99%

Effects of Magneto-Dielectric Ceramics for Small Antenna Application

Kim¹,

Lee²,

Lee³

et al. 2014

Journal of Electrical Engineering and Technology

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Chapter 5 Fundamental properties of hexagonal ferrites with magnetoplumbite structure

Cited by 188 publications

References 142 publications

Heat-treatment influence on the microstructure and magnetic properties of rare-earth substituted SrFe12O19

Heat-treatment influence on the microstructure and magnetic properties of rare-earth substituted SrFe12O19

Remarkable magnetic enhancement of type-M hexaferrite of barium in polystyrene polymer

Effects of Magneto-Dielectric Ceramics for Small Antenna Application

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