Abstract
Magnetic Co-beads were fabricated in the course of a three-step procedure comprising preparation of a metal–acrylamide complex, followed by frontal polymerization and finally pyrolysis of the polymer. The composites obtained were composed of cobalt nanocrystallites stabilized in a carbon matrix built of disordered graphite. The crystallite size, material morphology, fraction of the magnetic component, and thus the magnetic properties can be tailored by a proper choice of the processing variables. The samples were subjected to an alternating magnetic field of different strengths (H = 0 to 5 kA · m−1) at a frequency of f = 500 kHz. From the calorimetric measurements, we concluded that the relaxation processes dominate in the heat generation mechanism for the beads pyrolyzed at 773 K. For the beads pyrolyzed at 1073 K, significant values of magnetic properties, such as the coercive force and remanence give substantial contribution to the energy losses for hysteresis. The specific absorption coefficient (SAR) related to the cobalt mass unit for the 1073 K pyrolyzed beads \({({\it SAR} = 1340 \, \, {\rm W} \cdot {\rm g}^{-1 }_{\rm cobalt})}\) is in very good conformity with the results obtained by other authors. The effective density power loss, caused by eddy currents, can be neglected for heating processes applied in magnetic hyperthermia. The Co-beads can potentially be applied for hyperthermia treatment.
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Acknowledgments
Financial support from the Ministry of Science and Higher Education (Grant No. N N507 276136) is gratefully acknowledged. The studies were also supported by the Project for Polish-Slovak Bilateral Cooperation No. SK-PL-0069-09/8158/2010.
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Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
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Izydorzak, M., Skumiel, A., Leonowicz, M. et al. Thermophysical and Magnetic Properties of Carbon Beads Containing Cobalt Nanocrystallites. Int J Thermophys 33, 627–639 (2012). https://doi.org/10.1007/s10765-011-1110-z
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DOI: https://doi.org/10.1007/s10765-011-1110-z