Control of crystalline phases in magnetic Fe nanoparticles inserted inside a matrix of porous carbon |
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| Authors: | M.P. Fernández D.S. Schmool A.S. Silva M. Sevilla A.B. Fuertes P. Gorria J.A. Blanco |
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| Affiliation: | 1. Dpto. de Física, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo, Spain;2. IN-IFIMUP, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal;3. Dpto. de Física, Universidade do Porto, Rua do Campo Alegre 687, 4440-661 Porto, Portugal;4. Instituto Nacional del Carbon (CSIC), Apartado 73, 33080 Oviedo, Spain;1. Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), College of Chemistry & Materials Science, Northwest University, Xi’an 710127, PR China;2. National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), National Photoelectric Technology and Functional Materials & Application International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069, PR China;1. Department of Civil and Environmental Engineering, Temple University, 1947 North 12th Street, Philadelphia, PA 19122, United States;2. Department of Civil and Environmental Engineering, The George Washington University, 800 22nd St NW, Suite 3530, Science and Engineering Hall, Washington, DC 20052, United States;1. Laboratory of Toxicant and Drug Analysis – LATF, Gabriel Monteiro da Silva St. 700, Federal University of Alfenas – Unifal-MG, 37130-000 Alfenas, MG, Brazil;2. Institute of Chemistry, Gabriel Monteiro da Silva St. 700, Federal University of Alfenas – Unifal-MG, 37130-000 Alfenas, MG, Brazil;3. Brazilian Nanotechnology National Laboratory, 13083-970 Campinas, SP, Brazil;1. Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), Curtin University, GPO Box U1987, WA 6845, Australia;2. School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027, Australia;1. Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626 Villeurbanne, France;2. Université Clermont Auvergne, Sigma-Clermont, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France;3. CNRS, UMR 6296, ICCF, F-63178 Aubière, France;4. Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France;1. Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China;2. University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | Two magnetic composites made up of Fe nanoparticles (Fe-NPs) embedded in a porous amorphous carbon matrix are presented. One of the samples, Fe-S-AC, was obtained with the aid of sucrose and the other, Fe-AC, in the absence of this substance. The XRD patterns show Bragg diffraction peaks associated with α-Fe and γ-Fe crystalline phases in the Fe-AC sample, while only peaks corresponding to the α-Fe phase are observed for Fe-S-AC powders. The Fe-NPs exhibit broad particle-size distributions for both samples, 5–50 nm for Fe-AC, whereas two populations (2–8 and 10–70 nm) for the Fe-S-AC composite are found. This fact gives rise to poorly defined blocking temperatures, as it can be deduced from the broad maxima observed in MZFC(T) variations. In addition, M(H) curves for both Fe-AC and Fe-S-AC samples reveal the existence of exchange-bias effect for T<60 K, probably due to a magnetic coupling within a core/shell structure of the Fe-NPs, although this effect was observed to be less significant for Fe-S-AC. |
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