Microstructures and magnetic properties of Co–Cu nanoparticles prepared by arc-discharge

Yang, Zhiqing; You, Cai

doi:10.1016/j.jallcom.2005.12.048

Cited by 15 publications

(6 citation statements)

References 19 publications

(21 reference statements)

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“…3 This is in consistence with the findings that Co and Cu metals do not alloy [22][23][24]. 3 This is in consistence with the findings that Co and Cu metals do not alloy [22][23][24].…”

Section: Xrd Resultssupporting

confidence: 52%

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Synthesis of higher alcohols by the Fischer–Tropsch reaction over activated carbon supported CoCuMn catalysts

Pei¹,

Jian

Chen³

et al. 2015

RSC Adv.

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Activated carbon supported CoCuMn catalysts prepared by incipient co-impregnation were studied by using Fischer-Tropsch reaction, XRD, HR-TEM, and H 2 -TPR techniques. The results showed that good activities and selectivities towards C 1 -C 14 alcohols can be obtained with the fractions of C 2 -C 5 alcohols up to 80% in total alcohols. It is found that increasing the Cu/Co composition ratio resulted in the enhancement of alcohol selectivity. Furthermore, our characterizations revealed that large Cu nano-particles were decorated by small, spherical Co nano-particles, which we speculate that such construction were responsible for the favored formation of C 2+ alcohols. It is also considered that smaller cobalt particles probably resulted in more number of Co 0 and thus contributed to the improvement of CO conversion.

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“…3 This is in consistence with the findings that Co and Cu metals do not alloy [22][23][24]. 3 This is in consistence with the findings that Co and Cu metals do not alloy [22][23][24].…”

Section: Xrd Resultssupporting

confidence: 52%

“…This is consistent with the ndings that Co and Cu metals do not form an alloy. [22][23][24] No apparent peaks ascribed to manganese-containing species can be found, indicating that they were probably quite nely dispersed on the surface of the activated carbon support. Fig.…”

Section: Xrd Resultsmentioning

confidence: 99%

Synthesis of higher alcohols by the Fischer–Tropsch reaction over activated carbon supported CoCuMn catalysts

Pei¹,

Jian

Chen³

et al. 2015

RSC Adv.

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“…Nanomaterials are transforming modern science and technology due to their unique optical, electronic, catalytic, and magnetic properties that are not found in the corresponding bulk materials. − Among the various transition metal nanoparticles, copper is one of the most commonly studied materials . Copper nanoparticles can be used as catalysts, heat-transfer fluids, optical sensors, and as a substitute for more expensive metals such as Au, Ru, Rh, Pt, and Pd.…”

Section: Introductionmentioning

confidence: 99%

“…Compared to monometallic nanoparticles, bimetallic nanoparticles (either alloy or core–shell type structures) exhibit improved electronic, optical, physiochemical, and catalytic properties. ,− ,− ,− In addition, the nanoporosity of the shell is an interesting property of core–shell particles that promises to have great potential in the field of catalysis. Reactants and products can diffuse through the porous shell, thus allowing catalysis to occur at the peripheral or interfacial areas between the core and the shell .…”

Section: Introductionmentioning

confidence: 99%

Copper Core–Porous Manganese Oxide Shell Nanoparticles

et al. 2011

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Core–shell nanoparticles, especially those with nanoporous oxide shells, exhibit chemical and physical properties that are distinct from those of the bulk materials due to the atomic-level proximity and morphology of the core and shell atoms. Here, we demonstrate a wet-chemical method for the synthesis of Cu core (∼6.1 nm)–porous Mn3O4 shell (∼3.4 nm thick) nanoparticles. Various characterization techniques, including synchrotron radiation-based small-angle X-ray scattering (SAXS) and X-ray absorption near edge structure (XANES) tools, confirm the core–shell structure. Both the chemical and physical properties of these Cu-based nanoparticles are influenced by the Mn3O4 shell. For example, the magnetic properties of the core–shell particles are found to be similar to those of Mn3O4 nanoparticles reported in the literature. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results demonstrate that these materials are catalytically active for CO adsorption and hydrogenation.

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“…Let the free energy W be given by which is often referred to as Bloch's law (see [18,19]). Here B is the Bloch constant and is obviously dependent on the material.…”

Section: Evolution In the Three-dimensional Spacementioning

confidence: 99%

A thermodynamic approach to ferromagnetism and phase transitions

Fabrizio¹,

Giorgi²,

Morro³

2009

International Journal of Engineering Science

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The paper provides a modelling of the magnetization curve and of the ferromagnetic-paramagnetic transition within a continuum thermodynamic setting. The general model of the nonlinear, time dependent behaviour of ferromagnetic materials is accomplished by regarding the magnetization vector as an internal variable, namely as a vector field whose time evolution is a constitutive equation subject to the requirements of the second law of thermodynamics. The exchange interaction of the magnetization is modelled through a dependence of the free energy on the magnetization gradient. Consistent with the nonsimple character of the material, the second law allows for a non-zero extra-entropy flux. A general three-dimensional scheme is elaborated which seems to be new in the literature. The three-dimensional setting is then established for stationary and homogeneous fields thus finding the collinearity and the corresponding form of the magnetic susceptibility. The whole evolution problem for the temperature and the magnetization is provided so that temperature-induced transition processes are allowed. The model accounts also for the dependence of the saturation magnetization on the temperature. Also for the sake of comparison with the existing literature, the evolution equations for the direction and the intensity of magnetization are derived. Known models, such as those of Landau-Lifshitz and Gilbert, are recovered as particular cases of saturated bodies. Next, the model is made more specific so as to account in detail for the saturation, the residual or spontaneous magnetization and the coercive field. First, the classical potential, which traces back to Ginzburg, and the Weiss model are revisited. The corresponding lack of the saturation effect or the description via implicit relations are emphasized. Hence, a new potential, with a logarithmic dependence on the magnetization, is investigated which provides the residual magnetization and the coercive field in an explicit way and satisfies expected properties of the residual magnetization as a function of the temperature.

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Microstructures and magnetic properties of Co–Cu nanoparticles prepared by arc-discharge

Cited by 15 publications

References 19 publications

Synthesis of higher alcohols by the Fischer–Tropsch reaction over activated carbon supported CoCuMn catalysts

Synthesis of higher alcohols by the Fischer–Tropsch reaction over activated carbon supported CoCuMn catalysts

Copper Core–Porous Manganese Oxide Shell Nanoparticles

A thermodynamic approach to ferromagnetism and phase transitions

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