Role of the oxygen partial pressure in the formation of composite Co-CoO nanoparticles by reactive aggregation
| Autor: | J. M. Riveiro, J. P. Andrés, Marta Estrader, Ioannis Tsiaoussis, A. López–Ortega, Nikolaos Frangis, J. A. De Toro, Josep Nogués, J. A. González |
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| Rok vydání: | 2011 |
| Předmět: |
Nanocomposite
Materials science Nanopartícules Propietats magnètiques Magnetism Nanoparticle Bioengineering Nanotechnology General Chemistry Partial pressure Condensed Matter Physics Atomic and Molecular Physics and Optics Magnetization Chemical engineering Sputtering Transmission electron microscopy Modeling and Simulation Magnetic properties Nanoparticles Magnetic nanoparticles General Materials Science |
| Zdroj: | Dipòsit Digital de la UB Universidad de Barcelona Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 1572-896X 1388-0764 |
| DOI: | 10.1007/s11051-011-0418-8 |
| Popis: | 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. © 2011 Springer Science+Business Media B.V. |
| Databáze: | OpenAIRE |
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