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Title: Role of the oxygen partial pressure in the formation of composite Co-CoO nanoparticles by reactive aggregation
Author: Toro, J. A. de
Andrés, J. P.
González, J. A.
Riveiro, J. M.
Estrader i Bofarull, Marta
López-Ortega, Alberto
Tsiaoussis, I.
Frangis, N.
Nogués, Josep
Keywords: Nanopartícules
Propietats magnètiques
Magnetic properties
Issue Date: 22-May-2011
Publisher: Springer Verlag
Abstract: The magnetic properties of diluted films composed of nanocomposite Co-CoO nanoparticles (of ~8 nm diameter) dispersed in a Cu matrix have been investigated. The nanoparticles were formed in an aggregation chamber by sputtering at different Ar/O2 partial pressures (0-0.015). The exchange bias properties appear to be insensitive to the amount of O2 during their formation. However, the temperature dependence of the magnetization, M(T), exhibits two different contributions with relative intensities that correlate with the amount of O2. The magnetic results imply that two types of particles are formed, nanocomposite Co-CoO (determining the exchange bias) and pure CoO, as confirmed by transmission electron microscopy observations. Importantly, as the O2 partial pressure during the sputtering is raised the number of nanocomposite Co-CoO nanoparticles (exhibiting exchange bias properties) is reduced and, consequently, there is an increase in the relative amount of pure, antiferromagnetic CoO particles.
Note: Versió postprint del document publicat a:
It is part of: Journal Of Nanoparticle Research, 2011, vol. 13, num. 10, p. 4583-4590
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ISSN: 1388-0764
Appears in Collections:Articles publicats en revistes (Química Inorgànica i Orgànica)

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