CCVD Synthesis and Characterization of Cobalt-Encapsulated Nanoparticles

Flahaut, Emmanuel; Agnoli, F.; Sloan, Jeremy; O’Connor, Charles J.; Green, M. L. H.

doi:10.1021/cm011287h

Cited by 156 publications

(120 citation statements)

References 29 publications

(47 reference statements)

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“…Taking known values of saturation magnetization equal to 2.2 µ B for Fe, 1.7 µ B for Co and 0.6 µ B for Ni, one can see that for all samples under study M sat at T = 4.3 K is about 30% smaller than for bulk metal sample. A similar M sat decrease was observed for Co nanoparticles encapsulated in graphitized carbon shells prepared using the catalytic chemical vapor deposition (CCVD) method [6]. In all cases (see Table) decrease in the saturation moment is a bit stronger for the samples with higher carbon content.…”

Section: Magnetic Measurementssupporting

confidence: 69%

Magnetic Investigation of Carbon Coated Co-, Ni- and Fe-Nanoparticles

Makarewicz¹,

Podsiadły²,

Bałanda³

2009

Acta Phys. Pol. A

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Carbon coated cobalt-, nickel-and iron-nanoparticles were prepared by chemical method and their structural and magnetic properties were investigated. The samples were synthesized by carburization of the nanocrystalline form of the appropriate metal in CH4, followed up by the reduction of the obtained carbon deposits. The X-ray diffraction and transmission electron microscopy study revealed carbon coated Co-, Ni-and Fe-nanocapsules of the mean size ca. 50 nm, and a small amount of carbon nanotubes. The measurements of magnetization and AC susceptibility were carried out for samples with different carbon content. A special attention was paid to the low temperature magnetic behavior. Decrease in the saturation moment at T = 4.2 K due to the nanosize of the particles was stronger for the samples with higher carbon content, while the coercivity field (610 Oe, 330 Oe and 390 Oe, for Co-, Ni-, and Fe-particles, respectively) was independent of carbon content. From the temperature dependence of AC and DC susceptibility a wide size distribution of the particles and blocking temperature above room temperature could be expected.

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Section: Magnetic Measurementssupporting

confidence: 69%

Magnetic Investigation of Carbon Coated Co-, Ni- and Fe-Nanoparticles

Makarewicz¹,

Podsiadły²,

Bałanda³

2009

Acta Phys. Pol. A

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“…Although some researchers suggested that oxidative stress induced by CNTs may be caused by the presence of metal contaminants (or impurities) in the CNT instead [26,27], this is unlikely the cause of oxidative stress observed in the present study. More likely the reason is that the cobalt present in the DWNTs was carbon encapsulated and therefore unlikely to be bioavailable [3,19]. Based on the current results, DWNTs are possibly able to induce both oxidative and physical stress, which may result in the initiation of defense mechanisms.…”

Section: Discussionmentioning

confidence: 78%

“…Cobalt contaminants were present but were in the form of carbonencapsulated nanoparticles [3]. The carbon-encapsulated metal nanoparticles are tightly protected from the outside environment [19] and no leak of metal is expected in the experimental conditions used in this work. Autoclaved, filtered artificial seawater (30 ± 0.5%; pH 7.9-8.0) was used for all the experiments and was prepared by dissolving the appropriate amount of artificial sea salt in distilled water followed by filtration (sea salt: Tropic Marine, Germany; filter: glass microfiber filter GF/C 47 mm circle, Whatman, UK).…”

Section: Methodsmentioning

confidence: 99%

Chronic Toxicity of Double-Walled Carbon Nanotubes to Three Marine Organisms: Influence of Different Dispersion Methods

et al. 2010

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Aim: Double-walled carbon nanotubes (DWNTs) are found in a variety of consumer products, but there are no ecotoxicity data of DWNTs into marine organisms. Materials & methods: Chronic toxicity of DWNTs was investigated with the diatom Thalassiosira pseudonana, copepod Tigriopus japonicus and medaka Oryzias melastigma. DWNTs were dispersed using sonication (so-DWNTs) and stirring (st-DWNTs) for comparison. Results: The median aggregation size (0.89 µm2) of so-DWNTs was smaller than that of st-DWNTs (21.8 µm2). Exposure to DWNTs led to growth inhibition of T. pseudonana with EC50s of 1.86 and 22.7 mg/l for so- and st-DWNTs, respectively. Population growth of T. japonicus was reduced to 0.1 mg/l for so-DWNTs and 10 mg/l for st-DWNTs. Growth inhibition in O. melastigma was observed at 10 mg/l for so-DWNTs but not for st-DWNTs. Conclusion: Given that so-DWNTs are consistently significantly more toxic than st-DWNTs, dispersion method and size of aggregations should be considered in DWNT toxicity testing.

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“…90 wt%. This corresponds to more than 97.7 mol.% of carbon, assuming that the sample contains mainly Co and C. The remaining Co was assumed to be present only as carbon-encapsulated nanoparticles (Flahaut et al 2000(Flahaut et al , 2002. The BET (Brunauer Emmett Teller) specific surface area was 985 m 2 .g (1 .…”

Section: Cnts: Synthesis and Materials Used In This Studymentioning

confidence: 99%

Assessment of the potentialin vivoecotoxicity of Double-Walled Carbon Nanotubes (DWNTs) in water, using the amphibianAmbystoma mexicanum

et al. 2007

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Because of their specific properties (mechanical, electrical, etc), carbon nanotubes (CNTs) are being assessed for inclusion in many manufactured products. Due to their massive production and number of potential applications, the impact of CNTs on the environment must be taken into consideration. The present investigation evaluates the ecotoxic potential of CNTs in the amphibian larvae (Ambystoma mexicanum ). Acute toxicity and genotoxicity were analysed after 12 days of exposure in laboratory conditions. The genotoxic effects were analysed by scoring the micronucleated erythrocytes in the circulating blood of the larvae according to the French standard micronucleus assay. The results obtained in the present study demonstrated that CNTs are neither acutely toxic nor genotoxic to larvae whatever the CNTs concentration in the water, although black masses of CNTs were observed inside the gut. In the increasing economical context of CNTs, complementary studies must be undertaken, especially including mechanistic and environmental investigations.

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CCVD Synthesis and Characterization of Cobalt-Encapsulated Nanoparticles

Cited by 156 publications

References 29 publications

Magnetic Investigation of Carbon Coated Co-, Ni- and Fe-Nanoparticles

Magnetic Investigation of Carbon Coated Co-, Ni- and Fe-Nanoparticles

Chronic Toxicity of Double-Walled Carbon Nanotubes to Three Marine Organisms: Influence of Different Dispersion Methods

Assessment of the potentialin vivoecotoxicity of Double-Walled Carbon Nanotubes (DWNTs) in water, using the amphibianAmbystoma mexicanum

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