/ I. S. Edelman [et al.] // J. Appl. Phys. - 2012. -
Vol. 112,
Is. 8. - Ст. 84331. - P. ,
DOI 10.1063/1.4759244. - Cited References: 65. - This work was partly supported by the Russian Foundation for Basic Research, Grant Nos. 07-02-92174 RFBR-CNRS and 11-02-00972, and President of Russia Federation Grant No NSh 1044.2012.2. A. Artemenko acknowledges financial support from the Marie Curie International Incoming Fellowship within the 7th European Community Framework Programme (EPREXINA, GA 255662). The synchrotron measurements were supported via the Russian federal Contract No. 16.552.11.7003. The authors thank K. P. Polyakova for the preparation of thin films.
. - ISSN 0021-8979
РУБ Physics, Applied
Аннотация: A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD
spectra are related to different electron transitions in Fe3+ ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR
spectra corroborate the broad distribution of nanoparticle sizes found by "direct" techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the magnetization studies. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759244]
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Держатели документа: [Edelman, I.
Ivanova, O.
Ivantsov, R.
Velikanov, D.
Zabluda, V.] LV Kirensky Inst Phys SB RAS, Krasnoyarsk 660036, Russia
[Zubavichus, Y.
Veligzhanin, A.] NRC Kurchatov Inst, Moscow 123182, Russia
[Zaikovskiy, V.] Siberian Branch RAS, Boreskov Inst Catalysis, Novosibirsk 630090, Russia
[Stepanov, S.] SI Vavilov State Opt Inst, St Petersburg, Russia
[Artemenko, A.] CNRS, ICMCB, UPR 9048, F-33608 Pessac, France
[Curely, J.
Kliava, J.] Univ Bordeaux 1, CNRS, UMR 5798, LOMA, F-33405 Talence, France
Доп.точки доступа: Edelman, I. S.; Эдельман, Ирина Самсоновна; Ivanova, O. S.; Иванова, Оксана Станиславовна; Ivantsov, R. D.; Иванцов, Руслан Дмитриевич; Velikanov, D. A.; Великанов, Дмитрий Анатольевич; Zabluda, V. N.; Заблуда, Владимир Николаевич; Zubavichus, Y.; Veligzhanin, A. A.; Zaikovskiy, V. I.; Stepanov, S.; Artemenko, A.; Curely, J.; Kliava, J.
