<abstract xmlns="http://www.w3.org/1999/xhtml">The (nCo,N)-TiO2 (n = 1, 5 and 10 wt.% of Co) nanocomposites were investigated by magnetic resonance spectroscopy in 4 K to 290 K range. Analyses of ferromagnetic/electron paramagnetic resonance (FMR/EPR) spectra in terms of four Callen lineshape components revealed the existence of two types of magnetic centers, one derived from metallic cobalt nanoparticles in superparamagnetic (SPM) phase and the other from cobalt clusters in the TiO2 lattice. Additionally, at low temperature the EPR spectrum arising from Ti3+ ions was also registered. Both relaxations of the Landau-Lifshitz type and the Bloch-Bloembergen type played an important role at high temperature in determining the linewidths and the latter relaxation was prevailing at low temperature. Analysis of the integrated intensity showed that the SPM signal is due to small size FM cobalt nanoparticles while the paramagnetic signal from Co clusters originates from those nanoparticles in which the concentration of magnetic polarons is below the percolation threshold.</abstract>

The (nCo,N)-TiO2 (n = 1, 5 and 10 wt.% of Co) nanocomposites were investigated by magnetic resonance spectroscopy in 4 K to 290 K range. Analyses of ferromagnetic/electron paramagnetic resonance (FMR/EPR) spectra in terms of four Callen lineshape components revealed the existence of two types of magnetic centers, one derived from metallic cobalt nanoparticles in superparamagnetic (SPM) phase and the other from cobalt clusters in the TiO2 lattice. Additionally, at low temperature the EPR spectrum arising from Ti3+ ions was also registered. Both relaxations of the Landau-Lifshitz type and the Bloch-Bloembergen type played an important role at high temperature in determining the linewidths and the latter relaxation was prevailing at low temperature. Analysis of the integrated intensity showed that the SPM signal is due to small size FM cobalt nanoparticles while the paramagnetic signal from Co clusters originates from those nanoparticles in which the concentration of magnetic polarons is below the percolation threshold.

Temperature study of magnetic resonance spectra of co-modified (Co,N)-TiO2 nanocomposites

Department of Solid State Physics, Faculty of Physics, University of Athens, Panepistimioupolis, GR-157 84 Athens, Greece

Department of Physics, West Pomeranian University of Technology, al. Piastow 48, 70-311 Szczecin, Poland

Department of Chemical and Environmental Engineering, West Pomeranian University of Technology, al. Piastow 17, 70-310 Szczecin, Poland

Department of Electronic, Faculty of Physics, University of Athens, Panepistimioupolis, GR-157 84 Athens, Greece

Faculty of Electrical Engineering, West Pomeranian University of Technology, ul. Sikorskiego 37, 70-313 Szczecin, Poland

Materials Science-Poland

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Temperature study of magnetic resonance spectra of co-modified (Co,N)-TiO nanocomposites

The (nCo,N)-TiO2 (n = 1, 5 and 10 wt.% of Co) nanocomposites were investigated by magnetic resonance spectroscopy in 4 K to 290 K range. Analyses of...

Nanocomposite	Temperature 270 K		Temperature 5 K
Nanocomposite	Anisotropy field of center A [kG]	Anisotropy field of center B [kG]	Anisotropy field of center A [kG]	Anisotropy field of center B [kG]
1Co,N-TiO2	3	~0	6	2
5Co,N-TiO2	4.5	2.5	6	3
10Co,N-TiO2	5.5	2	6	3

Temperature study of magnetic resonance spectra of co-modified (Co,N)-TiO₂ nanocomposites

Article Category: Research Article

Publié en ligne: 27 juin 2016

Pages: 242 - 250

Reçu: 09 mars 2015

Accepté: 01 févr. 2016

DOI: https://doi.org/10.1515/msp-2016-0042

© Wroclaw University of Technology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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Anisotropy fields for centers A and B at high (270 K) and low temperature (5 K).