Journal ArticleDOI
Microstructure and Magnetic Properties of Lead Ferrite
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TLDR
In this article, the effects of small amounts of added oxides on the microstructure and magnetic properties of unoriented lead ferrite specimens were determined by calcining and sintering techniques, and it was shown that silica and boria form low melting phases as the specimens are sintered, which, acting as fluxes, enhance the densification of the magnets, thereby raising the Br, and (BaHa)max values.Abstract:
Unoriented lead ferrite specimens were prepared by calcining and sintering techniques. Specimens having an initial composition of Pb0.5Fe2O3 had the best permanent magnet properties (for nondoped material). The effects of small amounts of added oxides on the microstructure and magnetic properties were also determined. Silica and boria were most effective in raising the (BaHa)max to over 1.4 × 106 G.Oe as compared to 0.9 to 1.1 × 105 G.Oe for commercial un oriented barium ferrite magnets. Optical and electron microscopy revealed that silica and boria form low melting phases as the specimens are sintered, which, acting as fluxes (probably by a solution-precipitation mechanism), enhance the densification of the magnets, thereby raising the Br, and (BaHa)max, values. On cooling, these nonmagnetic low-melting phases are retained at the ferrite grain boundaries where they inhibit domain wall motion which would otherwise lead to a reduction in coercive force. Although these magnets are termed “un oriented” to distinguish them from “oriented” ferrites which are purposely aligned before sintering, a slight orientation is imparted to the polycrystalline compact during the pressing operation before sintering. The silica and boria additions increase the degree of orientation by accelerating the rate of densification. The increase in orientation accounts for part of the increase in Br, and (Ba, Ha)max.read more
Citations
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Journal ArticleDOI
Hexagonal ferrites: A review of the synthesis, properties and applications of hexaferrite ceramics
TL;DR: The most important members of the hexaferrite family are shown below, where Me = a small 2+ ion such as cobalt, nickel, or zinc, and Ba can be substituted by Sr: • M-type ferrites, such as BaFe12O19 (BaM or barium ferrite), SrFe 12O19(SrM or strontium ferite), and cobalt-titanium substituted M ferrite, Sr- or BaFe 12−2xCoxTixO19, or CoTiM as discussed by the authors.
Journal ArticleDOI
Influence of sintering time on structural, magnetic and electrical properties of Si–Ca added Sr-hexa ferrites
Shahid Hussain,Asghari Maqsood +1 more
TL;DR: Sr-hexa ferrites with the addition of Si (0.5 ) and Ca ( 0.5 ǫ ) have been prepared by solid-state reaction method with sintering time variation ranging from 2 to 10h as discussed by the authors.
Journal ArticleDOI
The effect of SiO2 addition on structural, magnetic and electrical properties of strontium hexa-ferrites
TL;DR: In this paper, the structural characterization of the samples confirmed the major phase of the Sr-hexa-ferrite and the average grain size was found within the range of micron.
Journal ArticleDOI
Effect of annealing temperature on the structural and magnetic properties of Ba-Pb-hexaferrite powders synthesized by sol-gel auto-combustion method
TL;DR: The phase purity, morphology and magnetic properties of BaxPb1-xFe12O19 powders synthesized via sol-gel auto-combustion route were studied in this article.
Journal ArticleDOI
Liquid‐phase sintering of magnetically isotropic and anisotropic compacts of BaFe12O19 and SrFe12O19
TL;DR: In this article, it was shown that magnetically isotropic and anisotropic compacts of BaFe12O19 or SrFe12 O19 sinter to high density with controlled microstructure in the presence of a liquid phase.
References
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Journal ArticleDOI
Hexagonal Iron-Oxide Compounds as Permanent-Magnet Materials
Journal ArticleDOI
Ferromagnetic properties of hexagonal iron-oxide compounds with and without a preferred orientation
TL;DR: Besprechung der Magnetisierung von hexagonalen Eisenoxydverbindungen als Funktion der Feldstarke is described in this paper, e.g.
Journal ArticleDOI
Cation substitutions in BaFe12O19
A.H. Mones,E. Banks +1 more
TL;DR: In this article, the variation in magnetic intensity of BaFe 12 O 19 was studied as a function of the substitution of ions such as Al III, Ga III, Cr III, and Zn II for Fe III.
Journal ArticleDOI
Modified strontium ferrite, a new permanent magnet material
TL;DR: A review of the magnetoplumbite magnet development from the early magnets of Takei to the recent high energy barium ferrite magnets of Tomholt is given in this paper.
Journal ArticleDOI
Phase Relations and Structures in the System PbO–Fe2O3
A. J. Mountvala,S. F. Ravitz +1 more
TL;DR: In this article, a detailed study of the PbO-Fe2O3 system was made by X-ray diffraction analysis, and the results indicated the existence of three intermediate phases: (1) a phase (beta) extending from Pb o·5Fe 2O3 to Pb O·6Fe 2 O3, (2) aphase (gamma) extending between Pbo -2Fe 2 o3 to pb o −21/2 2 O 3, and (3) phase (delta) 2PbO·