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Co Cores (co + core)

Distribution by Scientific Domains

Chemistry	60%

Selected Abstracts

Orientation Ordering of Nanoparticle Ag/Co Cores Controlled by Electric and Magnetic Fields

CHEMPHYSCHEM, Issue 7 2008
Katarína Gmucová Dr.
Abstract The effect of electric and magnetic fields on the sandwich structure Pt/hydrogenated amorphous silicon (a-Si:H)/stearic acid monolayer/Langmuir,Blodgett film of Ag/Co nanoparticles encapsulated in an organic envelope is studied. This structure is used as a working electrode in an electrochemical cell filled with NaCl solution (1 mM) and equipped with an Ag/AgCl reference electrode. Reversible changes in voltammograms are observed due to treatments (negative or positive bias voltage and simultaneous laser irradiation) applied to the designed structure before measurements. As an explanation of the observed phenomena we suggest that both the Co-up and Ag-up (on the a-Si:H surface) orientation orderings of nanoparticle Ag/Co cores are repeatedly reached. The role of the photovoltaic material (a-Si:H) in the observed behavior is explained. Voltammetric measurements with an applied magnetic field support our idea about the orientation ordering of nanoparticle cores. [source]

Magnetic properties of bimetallic Co-Pd nanostructures

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005
Javier Guevara
Abstract We study the dependence of the magnetic properties of Co-Pd nanoclusters (Co cores coated by Pd atoms) on size and relative composition. We consider Co-Pd clusters having closed shell cubo-octahedral structure with an increasing Co core size. The electronic and magnetic properties are calculated with a parametrized Hubbard Hamiltonian within the unrestricted Hartree-Fock approximation. We show that, depending on the relative composition, the Pd coating can give rise to an enhancement of the average magnetic moment of the Co core. We compare with results from slabs by using an ab initio calculation method. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The Thermal Decomposition of Three Magnetic Acetates at Their Autogenic Pressure Yields Different Products.

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2007

Abstract We report on the one-stage, reproducible, solvent-free, competent and straightforward approach for the synthesis of fullerene-like Ni@C, Co@C, and Fe3O4@C core-shell nanostructures that can be scaled up. The single precursor reactions of low cost acetates of Fe, Co and Ni are separately conducted at a relatively low temperature (700 °C) in a closed Swagelok reactor, as compared to other methods for the formation of graphitic layers. It is worth mentioning that although identical reaction parameters are employed, using the three acetate precursors, the graphitic carbon is coated on nanosized metallic Ni and Co cores, while Fe tends to form Fe3O4, maintaining the same core-shell morphology. The systematic morphological, compositional, structural characterization and the room temperature magnetic susceptibility measurements of the as-made particles are carried out on a vibrating sample magnetometer. The plausible mechanism is based on the comparison between the dissociation products of three acetate precursors, their obtained experimental data, and calculations on the enthalpy and free energy changes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]