Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

Journal Article · Mon Oct 15 00:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4759244· OSTI ID:22089501

Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V. ^[1]; Zubavichus, Y.; Veligzhanin, A. ^[2]; Zaikovskiy, V. ^[3]; Stepanov, S. ^[4]; Artemenko, A. ^[5]; Curely, J.; Kliava, J. ^[6]

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1. L.V. Kirensky Institute of Physics SB RAS, 660036 Krasnoyarsk (Russian Federation)
2. NRC 'Kurchatov Institute,' 123182 Moscow (Russian Federation)
3. Boreskov Institute of Catalysis, Siberian Branch of RAS, 630090 Novosibirsk (Russian Federation)
4. S.I. Vavilov State Optical Institute, St. Petersburg (Russian Federation)
5. ICMCB, UPR CNRS 9048, 33608 Pessac cedex (France)
6. LOMA, UMR 5798 Universite Bordeaux 1-CNRS, 33405 Talence cedex (France)

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 Fe{sup 3+} 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.

• OSTI ID: 22089501
• Journal Information: Journal of Applied Physics, Vol. 112, Issue 8; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
BISMUTH
COMPOSITE MATERIALS
DOPED MATERIALS
FERRITE GARNETS
GLASS
HOLMIUM
IRON
MAGNETIC CIRCULAR DICHROISM
MAGNETIC RESONANCE
MAGNETITE
MAGNETIZATION
NANOSTRUCTURES
PARAMAGNETISM
SUPERPARAMAGNETISM
TERBIUM
TRANSMISSION ELECTRON MICROSCOPY
X RADIATION
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
YTTRIUM