Change in Superparamagnetic State Induced by Swift Heavy Ion Irradiation in Nano-Maghemite
Sándor Stichleutner,
Bence Herczeg,
Jiří Pechoušek,
Libor Machala,
Zoltán Homonnay,
David Smrčka,
Lukáš Kouřil,
René Vondrášek,
Mátyás Kudor,
Vladimir A. Skuratov,
Luboš Krupa,
Shiro Kubuki,
Ernő Kuzmann
Affiliations
Sándor Stichleutner
Institute of Chemistry, Eötvös Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
Bence Herczeg
Institute of Chemistry, Eötvös Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
Jiří Pechoušek
Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
Libor Machala
Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
Zoltán Homonnay
Institute of Chemistry, Eötvös Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
David Smrčka
Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
Lukáš Kouřil
Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
René Vondrášek
Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
Mátyás Kudor
Institute of Chemistry, Eötvös Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
Vladimir A. Skuratov
Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, JINR, Joliot-Curie 6, 141980 Dubna, Russia
Luboš Krupa
Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic
Shiro Kubuki
Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1, Minami-Osawa, Hachi-Oji, Tokyo 192-0397, Japan
Ernő Kuzmann
Institute of Chemistry, Eötvös Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
The effect of swift heavy ion irradiation on sol–gel-prepared maghemite nanoparticles was studied by 57Fe transmission Mössbauer spectroscopy and X-ray diffractometry (XRD). The room temperature Mössbauer spectra of the non-irradiated nano-maghemite showed poorly resolved magnetically split, typical relaxation spectra due to the superparamagnetic state of the nanoparticles. Significant changes in the line shape, indicating changes in the superparamagnetic state, were found in the Mössbauer spectra upon irradiation by 160 MeV and 155 MeV 132Xe26+ ions with fluences of 5 × 1013 ion cm−2 and 1 × 1014 ion cm−2. XRD of the irradiated maghemite nanoparticles showed a significant broadening of the corresponding lines, indicating a decrease in the crystallite size, compared to those of the non-irradiated ones. The results are discussed in terms of the defects induced by irradiation and the corresponding changes related to the change in particle size and consequently in the superparamagnetic state caused by irradiation.
