Preparation and Characterization of Ultrafine Co and Ni Particles in a Polymer Matrix

Sarkar, Anjana; Kapoor, Sudhir; Yashwant, G.; Hg, Salunke; Mukherjee, Tulsi

doi:10.1021/jp044521a

Cited by 44 publications

(30 citation statements)

References 38 publications

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“…in high-density magnetic recording devices or magnetic sensors [1]. The unique properties of nanoparticles are determined primarily by the fact that most of the atoms in the particle belong to its surface [2].…”

Section: Introductionmentioning

confidence: 99%

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Nanocomposites of magnetic cobalt nanoparticles and cellulose

et al. 2008

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Abstract. Polymeric matrices with stabilized metallic nanoparticles constitute an important class of nanostructured materials, because polymer technology allows fabrication of components with various electronic, magnetic and mechanical properties. The porous cellulose matrix has been shown to be a useful support material for platinum, palladium, silver, copper and nickel nanoparticles. In the present study, nanosized cobalt particles with enhanced magnetic properties were made by chemical reduction within a microcrystalline cellulose (MCC) matrix. Two different chemical reducers, NaBH4 and NaH2PO2, were used, and the so-formed nanoparticles were characterized with X-ray absorption spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. These experimental techniques were used to gain insight into the effect of different synthesis routes on structural properties of the nanoparticles. Magnetic properties of the nanoparticles were studied using a vibrating sample magnetometer. Particles made via the NaBH4 reduction were amorphous Co-B or Co oxide composites with diminished ferromagnetic behaviour and particles made via the NaH2PO2 reduction were well-ordered ferromagnetic hcp cobalt nanocrystals.

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Section: Introductionmentioning

confidence: 99%

“…This method often leads to an inhomogenous dispersion of particles [1]. Thus considerable attention has been paid in the in situ chemical synthesis of metal nanoparticles in polymer matrices.…”

Section: Introductionmentioning

confidence: 99%

Nanocomposites of magnetic cobalt nanoparticles and cellulose

et al. 2008

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“…In many studies the nanoparticles have been self-supported (LesliePelecky & Rieke, 1996), but also nanocomposite materials where the nanoparticles are in e.g. a polymer matrix have been made (Sarkar et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Structure of nickel nanoparticles in a microcrystalline cellulose matrix studied using anomalous small-angle X-ray scattering

et al. 2007

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Nickel nanoparticles were synthesized by adding aqueous nickel salt into a microcrystalline cellulose matrix. The NiII ions were reduced with either sodium borohydride, NaBH, or potassium hypophosphite, KHPO, in water or aqueous NH medium. The mass fraction of Ni in the samples was between 3.7 and 8.9%. X‐ray absorption spectra at the Ni K‐edge showed that Ni was partially oxidized only in a sample reduced with NaBH. Wide‐angle X‐ray scattering results showed that nickel was in nanocrystalline or amorphous form in the samples. Upon heating fcc Ni, hcp Ni, NiO, NiP and other Ni–P phases formed depending on the reduction parameters. Using anomalous small‐angle X‐ray scattering the nanometre‐scale particle size distributions of the Ni particles were determined. A large fraction of particles less than 15 nm in size were observed in the samples reduced in aqueous ammonium compared with the samples reduced in water. Particles reduced in aqueous ammonium had a large ferromagnetic component.

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“…The magnetic moment of clusters is found to be higher than that of the bulk while that of nanoparticles is found to be lower than that of the bulk. [5][6][7][8][9][10][11][12][13][14] The saturation magnetization M S and the coercivity of Ni nanoparticles reported in literature vary from 15 to 46 emu g −1 and from 20 to 400 Oe, respectively. The variation in these magnetic parameters is due to the different synthesis techniques used and the nature of encapsulation of the Ni particles.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear spin wave magnetization of solution synthesized Ni nanoparticles

Vitta

2007

Journal of Applied Physics

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The magnetic properties of Ni nanoparticles synthesized using a soft chemical method followed by heat treatment in H 2 atmosphere have been studied in detail. The powder consists of pure Ni with no additional phase and the average crystallite size is 30± 5 nm, determined using the modified Scherer relation. The crystallites tend to agglomerate into large particles of sizes 50-100 nm, as observed by transmission electron microscopy. The saturation magnetization is found to be 46.42 emu g −1 at 5 K, about 80% of the bulk magnetization value. The temperature dependence of saturation magnetization for T Ͻ 0.5T C is found to deviate from the linear Bloch's T 3/2 law indicating that spin wave interactions needs to be considered to understand the behavior. The spin wave stiffness constant obtained by fitting the saturation magnetization decay to a nonlinear spin wave model is lower by an order of magnitude compared to that of bulk Ni. The coercivity on the other hand decreases from 67 Oe at 5 K to 36 Oe at 300 K with a temperature dependence slower than the T 1/2 behavior predicted for noninteracting superparamagnetic particles.

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Preparation and Characterization of Ultrafine Co and Ni Particles in a Polymer Matrix

Cited by 44 publications

References 38 publications

Nanocomposites of magnetic cobalt nanoparticles and cellulose

Nanocomposites of magnetic cobalt nanoparticles and cellulose

Structure of nickel nanoparticles in a microcrystalline cellulose matrix studied using anomalous small-angle X-ray scattering

Nonlinear spin wave magnetization of solution synthesized Ni nanoparticles

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