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Title: Size and surface effects on the magnetism of magnetite and maghemite nanoparticles

Abstract

The size effects of magnetite and maghemite nanoparticles on their magnetic properties (magnetic moment, Curie temperature, blocking temperature, etc.) have been investigated. Magnetic separation and centrifugation of an aqueous solution of nanoparticles were used for their separation into fractions; their sizes were measured by atomic force microscopy, dynamic light scattering, and electron microscopy. A change in the size leads to a change in the Curie temperature and magnetic moment per formula unit. Both native nanoparticles and those covered with a bioresorbable layer have been considered. The magnetic properties have been calculated by the Monte Carlo method for the classical Heisenberg model with various bulk and surface magnetic moments.

Authors:
 [1]; ;  [2]
  1. Moscow State University (Russian Federation)
  2. Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)
Publication Date:
OSTI Identifier:
22617064
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 124; Journal Issue: 2; Other Information: Copyright (c) 2017 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; AQUEOUS SOLUTIONS; ATOMIC FORCE MICROSCOPY; CENTRIFUGATION; CHANNELING; CURIE POINT; ELECTRON MICROSCOPY; ELECTRONS; HEISENBERG MODEL; LAYERS; LIGHT SCATTERING; MAGNETIC MOMENTS; MAGNETIC PROPERTIES; MAGNETISM; MAGNETITE; MONTE CARLO METHOD; NANOPARTICLES; SURFACES

Citation Formats

Nikiforov, V. N., E-mail: pppnvn@yandex.ru, Ignatenko, A. N., and Irkhin, V. Yu.. Size and surface effects on the magnetism of magnetite and maghemite nanoparticles. United States: N. p., 2017. Web. doi:10.1134/S1063776117010046.
Nikiforov, V. N., E-mail: pppnvn@yandex.ru, Ignatenko, A. N., & Irkhin, V. Yu.. Size and surface effects on the magnetism of magnetite and maghemite nanoparticles. United States. doi:10.1134/S1063776117010046.
Nikiforov, V. N., E-mail: pppnvn@yandex.ru, Ignatenko, A. N., and Irkhin, V. Yu.. Wed . "Size and surface effects on the magnetism of magnetite and maghemite nanoparticles". United States. doi:10.1134/S1063776117010046.
@article{osti_22617064,
title = {Size and surface effects on the magnetism of magnetite and maghemite nanoparticles},
author = {Nikiforov, V. N., E-mail: pppnvn@yandex.ru and Ignatenko, A. N. and Irkhin, V. Yu.},
abstractNote = {The size effects of magnetite and maghemite nanoparticles on their magnetic properties (magnetic moment, Curie temperature, blocking temperature, etc.) have been investigated. Magnetic separation and centrifugation of an aqueous solution of nanoparticles were used for their separation into fractions; their sizes were measured by atomic force microscopy, dynamic light scattering, and electron microscopy. A change in the size leads to a change in the Curie temperature and magnetic moment per formula unit. Both native nanoparticles and those covered with a bioresorbable layer have been considered. The magnetic properties have been calculated by the Monte Carlo method for the classical Heisenberg model with various bulk and surface magnetic moments.},
doi = {10.1134/S1063776117010046},
journal = {Journal of Experimental and Theoretical Physics},
number = 2,
volume = 124,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • In the present work, we investigate the magnetic properties of ferrimagnetic and non-interacting maghemite hollow nanoparticles obtained by the Kirkendall effect. From the experimental characterization of their magnetic behavior, we find that polycrystalline hollow maghemite nanoparticles exhibit low blocked-to-superparamagnetic transition temperatures, small magnetic moments, significant coercivities and irreversibility fields, and no magnetic saturation on external magnetic fields up to 5 T. These results are interpreted in terms of the microstructural parameters characterizing the maghemite shells by means of atomistic Monte Carlo simulations of an individual spherical shell. The model comprises strongly interacting crystallographic domains arranged in a spherical shell withmore » random orientations and anisotropy axis. The Monte Carlo simulation allows discernment between the influence of the polycrystalline structure and its hollow geometry, while revealing the magnetic domain arranggement in the different temperataure regimes.« less
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  • Monte Carlo simulations of a model for {gamma}-Fe{sub 2}O{sub 3} (maghemite) single particle of spherical shape are presented aiming at the elucidation of the specific role played by the finite size and the surface on the anomalous magnetic behavior observed in small particle systems at low temperature. The influence of the finite-size effects on the equilibrium properties of extensive magnitudes, field coolings, and hysteresis loops is studied and compared to the results for periodic boundaries. It is shown that for the smallest sizes the thermal demagnetization of the surface completely dominates the magnetization while the behavior of the core ismore » similar to that of the periodic boundary case, independently of D. The change in shape of the hysteresis loops with D demonstrates that the reversal mode is strongly influenced by the presence of broken links and disorder at the surface. {copyright} 2001 American Institute of Physics.« less
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