Acicular gamma -Fe/sub 2/O/sub 3/ particles surface-coated with barium ferrite

Deng, M.C.; Hsu, S.L.; Chin, Tsung‐Shune

doi:10.1109/20.179500

Cited by 13 publications

(4 citation statements)

References 7 publications

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“…Nonsphericity is an essential criterion for enhancing signal to noise ratio during recording (Bate 1991;Deng et al 1992). But γ-Fe 2 O 3 is a cubic crystal and does not easily form into elongated ellipsoidal particles.…”

Section: Introductionmentioning

confidence: 99%

Strain induced anomalous red shift in mesoscopic iron oxide prepared by a novel technique

et al. 2008

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Nano magnetic oxides are promising candidates for high density magnetic storage and other applications. Nonspherical mesoscopic iron oxide particles are also candidate materials for studying the shape, size and strain induced modifications of various physical properties viz. optical, magnetic and structural. Spherical and nonspherical iron oxides having an aspect ratio, ~2, are synthesized by employing starch and ethylene glycol and starch and water, respectively by a novel technique. Their optical, structural, thermal and magnetic properties are evaluated. A red shift of 0⋅24 eV is observed in the case of nonspherical particles when compared to spherical ones. The red shift is attributed to strain induced changes in internal pressure inside the elongated iron oxide particles. Pressure induced effects are due to the increased overlap of wave functions. Magnetic measurements reveal that particles are superparamagnetic. The marked increase in coercivity in the case of elongated particles is a clear evidence for shape induced anisotropy. The decreased specific saturation magnetization of the samples is explained on the basis of weight percentage of starch, a nonmagnetic component and is verified by TGA and FTIR studies. This technique can be modified for tailoring the aspect ratio and these particles are promising candidates for drug delivery and contrast enhancement agents in magnetic resonance imaging.

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Section: Introductionmentioning

confidence: 99%

Strain induced anomalous red shift in mesoscopic iron oxide prepared by a novel technique

et al. 2008

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“…Acicularity in turn determines the signal to noise ratio, since needle-shaped particles can give rise to higher coercive force and better alignment of particles, which in turn produce less noise during recording (Deng et al 1992). The topotactic decomposition of acicular precursors results in acicular particles with the required size and shape.…”

Section: Introductionmentioning

confidence: 99%

A new inexpensive method for the preparation of acicular precursors for magnetic recording media

1997

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Abstract. Magnetic materials meant for audio/video recording applications necessitate that polycrystalline materials be in acicular shape. So preparation of acicular precursors for magnetic storage materials assumes significance. The employment of aqueous solutions do not produce needle shape crystallites. Glycerol is one of the complexing media used for the precipitation of ferrous oxalate dihydrate. An inexpensive method using starch for preparation of acicular particles is described. The influence of an additive namely Gd on acicularity is also investigated.

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“…Many methods can be used to synthesize BaFe 12 O 19 , and co-precipitation and sol-gel methods are most widely used [5−7]. By precipitation-toptactic reaction method developed from the co-precipitation method with mixing components in ionic states and precise measurements of every component and chemical activity, the appearance of final products can be controlled [8,9]. Using this method precursors have to be prepared by mixing the *Corresponding author (email: xiaohuicao@hotmail.com) pod-like ferric oxide with Barium salt and then annealed to produce pod-like barium ferrites.…”

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confidence: 99%

Synthesis process of Ba-ferrites from α-FeOOH and γ-FeOOH and investigation of magnetic properties

et al. 2010

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The claviform BaFe 12 O 19 crystals were synthesized by the precipitation-toptactic reaction method using α-FeOOH and γ-FeOOH as raw materials respectively. The synthesis processes of BaFe 12 O 19 , studied by XRD, SEM, EDS, FT-IR, and TG-DTA techniques, included preparations of precursor γ and precursor α, formations of α-Fe 2 O 3 and BaFe 2 O 4 , and production of rod-like BaFe 12 O 19 through dehydroxylation of pod-like FeOOH, followed by reactions of α-Fe 2 O 3 with BaCO 3 and BaFe 2 O 4 . The crystallinity of α-Fe 2 O 3 and BaCO 3 from precursor α was better than from precursor γ due to the direct dehydroxylation of α-FeOOH, resulting in a lower nucleation rate and better crystallinity of BaFe 2 O 4 . BaFe 12 O 19 prepared from precursor α showed lower crystallinity and purity with a higher length-diameter ratio than from precursor γ. The VSM results proved that the appearance of final products had an important influence on magnetic properties. Ba-ferrite, formed processes, synthesize, phase change Citation:Cao X H, Tan Y Z, Meng J H, et al. Synthesis process of Ba-ferrites from α-FeOOH and γ-FeOOH and investigation of magnetic properties.

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Acicular gamma -Fe/sub 2/O/sub 3/ particles surface-coated with barium ferrite

Cited by 13 publications

References 7 publications

Strain induced anomalous red shift in mesoscopic iron oxide prepared by a novel technique

Strain induced anomalous red shift in mesoscopic iron oxide prepared by a novel technique

A new inexpensive method for the preparation of acicular precursors for magnetic recording media

Synthesis process of Ba-ferrites from α-FeOOH and γ-FeOOH and investigation of magnetic properties

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