A comparative study of nanosized iron oxide particles; magnetite (Fe3O4), maghemite (gamma-Fe2O3) and hematite (alpha-Fe2O3), using ferromagnetic resonance


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Can M. M., Coskun M., Firat T.

JOURNAL OF ALLOYS AND COMPOUNDS, vol.542, pp.241-247, 2012 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 542
  • Publication Date: 2012
  • Doi Number: 10.1016/j.jallcom.2012.07.091
  • Journal Name: JOURNAL OF ALLOYS AND COMPOUNDS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.241-247
  • Keywords: Magnetic resonance line symmetry, Intra and inter particle interactions, Iron oxide nanoparticles, NANOPARTICLES, SURFACE, TEMPERATURE, COERCIVITY, FERROFLUID, ANISOTROPY, OXIDATION, BEHAVIOR, SIZE
  • Istanbul University Affiliated: No

Abstract

We investigated intra/inter particle interactions in single domain size magnetite (Fe3O4), maghemite (γ-Fe2O3) and hematite (α-Fe2O3) iron oxide particles. The magnetic analyses were done using vibrating sample magnetometer and magnetic resonance measurements that were taken from 5 to 300 K and from 120 to 300 K, respectively. The magnetic resonance analyses were done for the iron oxides, frozen under 5000 G fields in glycerol matrix. By changing the temperature, a change in resonance field lines was observed at each Fe3O4, γ-Fe2O3 and α-Fe2O3 nanoparticles. However, the fits in resonant lines showed that Landé g values (spectroscopic splitting factor) stayed stable with temperature decrease. The thermal sensitivities that were determined from Landé gfactors, revealed three dominant interactions on resonant lines namely; the exchange coupling in between Fe2+, Fe3+ and O (g1 = 3.01 ± 0.08), Fe3+ centers (1.88 ± 0.03 ? g2 ? 2.02 ± 0.03, depending on iron oxide states) and flip flop of O ions in between ionic states of Fe2+–O−1 and Fe3+–O−2 (2.35 ± 0.06 ? g3 ? 2.44 ± 0.06, depending on iron oxide states).

We investigated intra/inter particle interactions in single domain size magnetite (Fe3O4), maghemite (gamma-Fe2O3) and hematite (alpha-Fe2O3) iron oxide particles. The magnetic analyses were done using vibrating sample magnetometer and magnetic resonance measurements that were taken from 5 to 300 K and from 120 to 300 K, respectively. The magnetic resonance analyses were done for the iron oxides, frozen under 5000 G fields in glycerol matrix. By changing the temperature, a change in resonance field lines was observed at each Fe3O4, gamma-Fe2O3 and alpha-Fe2O3 nanoparticles. However, the fits in resonant lines showed that Lande g values (spectroscopic splitting factor) stayed stable with temperature decrease. The thermal sensitivities that were determined from Lande g factors, revealed three dominant interactions on resonant lines namely; the exchange coupling in between Fe2+, Fe3+ and O (g(1) = 3.01 +/- 0.08), Fe3+ centers (1.88 +/- 0.03 <= g(2) <= 2.02 +/- 0.03, depending on iron oxide states) and flip flop of O ions in between ionic states of Fe2+-O (1) and Fe3+-O (2) (2.35 +/- 0.06 <= g(3) <= 2.44 +/- 0.06, depending on iron oxide states). (C) 2012 Elsevier B.V. All rights reserved.