Effect of Growth Rate on Saturation Magnetization of Fe Nanoparticles

Ogawa, Tomoyuki; Seto, K.; Hasegawa, D.; Hu, Yang; Takahashi, M.

doi:10.3379/msjmag.0903rd8055

Cited by 4 publications

(7 citation statements)

References 14 publications

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“…From a previous theoretical literature [7], the size of nuclei is reported to be around 1 nm, which is much small than our experimental result of 3.8 nm in average. This difference may be attributed to the contribution of fast nucleation process in the most initial stage just after the injection of Fe(CO) 5 into the reaction solution. Therefore, fast nucleation process and slow particle growth process could have a possibility to be coexistent of non-equilibrium and equilibrium phases, and have different saturation magnetizations between the initial nucleus and the growth layer covering the nucleus.…”

Section: Resultsmentioning

confidence: 99%

“…And slow particle growth with atomicscaled surface precipitation mode (< 100 atoms/(min·nm 2 )) can form the growth layer on the surface of initial nucleus with high saturation magnetization (~190 emu/g Fe ) as an equilibrium a phase of Fe. Therefore, higher stabilization of small initial nucleus generated just after the injection of Fe(CO) 5 should be one of the key issues to achieve much higher M s of Fe NPs.…”

Section: Resultsmentioning

confidence: 99%

“…to 60 min. Residual amount of Fe(CO) 5 , i.e., number of precursor Fe(CO) 5 in the reaction solution (n m ) was quantitatively evaluated by an infra-red (IR) spectra [5]. The Fe NPs covered with surfactant were re-dispersed into kerosene matrix solution after washing by an appropriate amount of acetone.…”

Section: Experimental and Analysis Proceduresmentioning

confidence: 99%

“…Fe NPs were synthesized by our developed thermal decomposition method [3] using an iron carbonyl Fe(CO) 5 , whose total number of injected Fe atoms (hereafter, denoted as n 0 ) was systematically changed from 0.61 × 10 21 (1 mmol) to 4.30 × 10 21 (10 mmol), treated in a glove box under Ar atmosphere with 0.1 ppm -1 ppm of O 2 and H 2 O [3]. 180 deg C of refluxing temperature was fixed and refluxing time was changed from 1 min.…”

Section: Experimental and Analysis Proceduresmentioning

confidence: 99%

“…In order to obtain a high permeability, high saturation magnetization (M S ) of the NP is required, and pure α phase of Fe is one of the attractive candidates. However, 20-30% of smaller values of the Ms than that of bulk (220 emu/g Fe ) have been obtained for the chemically synthesized Fe NPs using a Fe(CO) 5 as precursor in spite of minimal oxidation during the synthesis [3,4]. Thus, it is necessary to clarify not only the phase of the individual NP but also the relationship between growth process of the phase and Ms.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Nucleation and Growth Dynamics on Saturation Magnetization of Chemically Synthesized Fe Nanoparticles

Ogawa¹,

Seto²,

Hasegawa³

et al. 2011

Journal of Magnetics

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In order to obtain mono-dispersed Fe NPs with high saturation magnetization, quantitative analysis method to investigate the growth dynamics of the Fe NPs synthesized by a conventional thermal decomposition method has been developed. As a result, fast nucleation process promotes formation of ~4 nm of initial nucleus with a non-equilibrium phase, resulting in low saturation magnetization. And slow particle growth with atomic-scaled surface precipitation mode (< 100 atoms/(min·nm 2 )) can form the growth layer on the surface of initial nucleus with high saturation magnetization (~190 emu/g Fe ) as an equilibrium a phase of Fe. Therefore, higher stabilization of small initial nucleus generated just after the injection of Fe(CO) 5 should be one of the key issues to achieve much higher M s of Fe NPs.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Experimental and Analysis Proceduresmentioning

confidence: 99%

Section: Experimental and Analysis Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of Nucleation and Growth Dynamics on Saturation Magnetization of Chemically Synthesized Fe Nanoparticles

Ogawa¹,

Seto²,

Hasegawa³

et al. 2011

Journal of Magnetics

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Synthesis of Monodisperse Iron Nanoparticles with a High Saturation Magnetization Using an Fe(CO)_x−Oleylamine Reacted Precursor

2010

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Monodisperse Fe nanoparticles with a high saturation magnetization were synthesized by thermal decomposition of a newly developed Fe(CO) x -oleylamine reacted precursor. The coordinate bond of the Fe(CO) x -oleylamine reacted precursor is different from conventional Fe(CO) 5 , and the CO ligands are partially replaced by oleylamine. The coordinate bond of the Fe(CO) x -oleylamine reacted precursor had a large influence on the size of the Fe nanoparticles, and as a result, the nanoparticle diameter could be controlled in the range from 2.3 to 10 nm by changing the reaction temperature and time for the precursor. The saturation magnetizations for 10 and 2.3 nm diameter NPs were 192 and 160 emu/g Fe at 5 K. The high M S of the Fe NPs was attributed to lesser amounts of impurities, such as C and O.

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Wide Range Diameter Control of Monodisperse Fe Nanoparticles Synthesized by Thermal Decomposition of Fe(CO)<sub>5</sub>

2012

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Two different approaches to obtain monodisperse Fe nanoparticles (NPs) in a wide range of average diameters based on thermal decomposition of Fe(CO)5 were developed; the first is thermal decomposition of a Fe(CO)5 -oleylamine (OAm) reacted precursor, and the second is a method of Fe(CO)5 slow injection. OAm as a surfactant strongly adsorbed on an Fe atom in the thermal decomposition of a Fe(CO)5-OAm reacted precursor and restricted the particle growth process. As a result, small NPs 2.3 nm in diameter were obtained. Moreover, it was possible to control the NP diameter in the range from 2.3 to 10 nm by changing the reaction temperature and the time for precursor preparation. However, large NPs over 20 nm in diameter were obtained with the method of slow injection by promoting the process of particle growth. Controls for the density of dissolved Fe atoms and Fe NPs in a reaction solution were required to accelerate particle growth without nucleation. Modifications to the injection rate and/or thermal decomposition temperature of Fe(CO)5 thus enabled us to control the NP diameter in the range from 12 to 21 nm.

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Effect of Growth Rate on Saturation Magnetization of Fe Nanoparticles

Cited by 4 publications

References 14 publications

Effect of Nucleation and Growth Dynamics on Saturation Magnetization of Chemically Synthesized Fe Nanoparticles

Effect of Nucleation and Growth Dynamics on Saturation Magnetization of Chemically Synthesized Fe Nanoparticles

Synthesis of Monodisperse Iron Nanoparticles with a High Saturation Magnetization Using an Fe(CO)_x−Oleylamine Reacted Precursor

Wide Range Diameter Control of Monodisperse Fe Nanoparticles Synthesized by Thermal Decomposition of Fe(CO)<sub>5</sub>

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Effect of Growth Rate on Saturation Magnetization of Fe Nanoparticles

Cited by 4 publications

References 14 publications

Effect of Nucleation and Growth Dynamics on Saturation Magnetization of Chemically Synthesized Fe Nanoparticles

Effect of Nucleation and Growth Dynamics on Saturation Magnetization of Chemically Synthesized Fe Nanoparticles

Synthesis of Monodisperse Iron Nanoparticles with a High Saturation Magnetization Using an Fe(CO)x−Oleylamine Reacted Precursor

Wide Range Diameter Control of Monodisperse Fe Nanoparticles Synthesized by Thermal Decomposition of Fe(CO)<sub>5</sub>

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Synthesis of Monodisperse Iron Nanoparticles with a High Saturation Magnetization Using an Fe(CO)_x−Oleylamine Reacted Precursor