Effect of Carbonate Ion in Colloidal Mother Liquid on Formation of Acicular .ALPHA.-FeOOH Particles.

Iwasaki, Kazuharu; Yamamura, Tsutomu

doi:10.2497/jjspm.46.247

Cited by 4 publications

(3 citation statements)

References 11 publications

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“…Acicular -FeOOH particles were synthesized by aging a colloidal amorphous ferric oxyhydroxide solution which was prepared by neutralizing a FeCl 3 aqueous solution and a NaOH solution [15][16][17][18][19][20][21] at a predetermined temperature, and a sample was made by surface-treating the particles in the following manner, using the acicular -FeOOH particles.…”

Section: Sample Preparationmentioning

confidence: 99%

Production Conditions of Acicular Magnetic Metal Nanoparticles for Magnetic Recording

2005

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Hydrogen reduction conditions of -Fe 2 O 3 particles and surface passivation conditions of metal nanoparticles obtained through a hydrogen reduction process of acicular -Fe 2 O 3 particles and a slow oxidation process in a low oxygen concentration have been studied in order to determine optimum production conditions of acicular magnetic metal nanoparticles utilized for magnetic recording.Acicular magnetic metal nanoparticles were produced by using the surface-treated acicular -FeOOH nanoparticles containing 12.6 at%Co-9.4 at%Si-7.0 at%Al under the condition of 823 K in temperature of dehydration of -FeOOH particles by heating, 5 Â 10 À6 m 3 (STP)Ás À1 in flow rate, 50 mol%H 2 -50 mol%Ar in composition of a reducing gas, and 823 K in reduction temperature. The resulting reduced metal particles are composed of either a single crystal or polycrystals. The inside of the particles was a reduced dense metal phase in which the crystal growth with neither defect nor pore was sufficiently proceeded.The surface oxide layer of metal particles which is formed by the slow oxidation results in a spinel structure of Fe 3 O 4 . The metallic core was entirely coated by the surface oxide layer, and it was observed that the dense crystal having no defect; pore and so forth inside the oxide layer was sufficiently grown. It is assumed that a passivation layer possessing a higher corrosion-resistant property can be obtained with a thicker surface oxide layer, since the oxide layer on the surface of the metal nanoparticle becomes thicker with higher temperature of slow oxidation.Acicular magnetic metal nanoparticles having the excellent property of corrosion resistance were able to be produced under the condition of 338 K in oxidation temperature, 5 Â 10 À6 m 3 (STP)Ás À1 in flow rate and 0.5 mol%O 2 -99.5 mol%N 2 in composition of oxidizing gas.

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Section: Sample Preparationmentioning

confidence: 99%

Production Conditions of Acicular Magnetic Metal Nanoparticles for Magnetic Recording

2005

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“…(4) can be applicable to the formation reaction of α-FeOOH crystalline particles. [1][2][3][4][5][6]19) …”

Section: Effects Of Addition Of Cobalt Ion On Formation Rate and Crysmentioning

confidence: 99%

“…[1][2][3][4][5][6] The addition of foreign ions to the mother liquid can be considered as one of the available shape control methods for α-FeOOH particles. As for anions, the adsorption mechanism of phosphate, sulfate and carbonate ions on the α-FeOOH crystalline surface has been reported.…”

Section: Introductionmentioning

confidence: 99%

Whisker-Like Goethite Nanoparticles Containing Cobalt Synthesized in a Wet Process

Iwasaki

Yamamura

2002

Mater. Trans.

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Acicular α-FeOOH particles are formed through aging of ferric oxyhydroxide colloidal solution formed by the neutralization of FeCl 3 aqueous solution by NaOH. The effects of cobalt ion addition in the sol-gel-sol process on the formation rate and morphology of α-FeOOH nanoparticles have been investigated. The magnetic properties of metal nanoparticles prepared from the obtained particles have also been examined. The dependence of reaction rate constants in the formation of α-FeOOH in the wet process and the crystallite size of (110) on Co content in α-FeOOH has been made clear. Both the rate constant and crystallite size decrease with increasing Co content in α-FeOOH particles. The negative zeta-potential of the formed α-FeOOH particles increases slowly with increasing pH of the electrolytic solution. The negative zeta-potential of α-FeOOH particles containing Co is larger than that of α-FeOOH particles without Co in the range of pH6-pH12. The relationship between the morphology of the formed α-FeOOH particles and the cobalt content in α-FeOOH particles has been investigated. The length of major axis increases and the length of minor axis decreases with increasing Co content, and the aspect ratio increases remarkably. It is likely that Fe(OH) − 4 complex ion precipitates preferentially on the c plane, and the particles grow remarkably in the direction of c axis. The interplanar spacing of the α-FeOOH decreases with increasing Co content. The formed α-FeOOH grows abnormally like whisker in the direction of major axis: c axis in the case of significantly much Co content: 27 at%, and also the whisker like nanoparticles are observed to grow with curving. The magnetic metal nanoparticles produced have excellent dispersivity and high aspect ratio. The metal nanoparticles have magnetic properties enough for the magnetic recording media.

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Heterogeneously Junctioned Nano-Particles of Hematite and Goethite Formed in a Wet Process

Iwasaki

Itoh

Yamamura³

2001

Mater. Trans.

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Effect of Carbonate Ion in Colloidal Mother Liquid on Formation of Acicular .ALPHA.-FeOOH Particles.

Cited by 4 publications

References 11 publications

Production Conditions of Acicular Magnetic Metal Nanoparticles for Magnetic Recording

Production Conditions of Acicular Magnetic Metal Nanoparticles for Magnetic Recording

Whisker-Like Goethite Nanoparticles Containing Cobalt Synthesized in a Wet Process

Heterogeneously Junctioned Nano-Particles of Hematite and Goethite Formed in a Wet Process

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