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Hybrid magnetic iron oxide nanoparticles with tunable field-directed self-assembly

Malik, Vikash; Pal, Antara LU ; Pravaz, Olivier; Crassous, Jerome LU ; Granville, Simon; Grobety, Bernard; Hirt, Ann M; Dietsch, Hervé and Schurtenberger, Peter LU (2017) In Nanoscale 9(38). p.14405-14413
Abstract
We describe the synthesis of hybrid magnetic ellipsoidal nanoparticles that consist of a mixture of two different iron oxide phases, hematite (α-Fe2O3) and maghemite (γ-Fe2O3), and characterize their magnetic field-driven self-assembly. We demonstrate that the relative amount of the two phases can be adjusted in a continuous way by varying the reaction time during the synthesis, leading to strongly varying magnetic properties of the particles. Not only does the saturation magnetization increase dramatically as the composition of the spindles changes from hematite to maghemite, but also the direction of the induced magnetic moment changes from being parallel to the short axis of the spindle to being perpendicular to it. The magnetic dipolar... (More)
We describe the synthesis of hybrid magnetic ellipsoidal nanoparticles that consist of a mixture of two different iron oxide phases, hematite (α-Fe2O3) and maghemite (γ-Fe2O3), and characterize their magnetic field-driven self-assembly. We demonstrate that the relative amount of the two phases can be adjusted in a continuous way by varying the reaction time during the synthesis, leading to strongly varying magnetic properties of the particles. Not only does the saturation magnetization increase dramatically as the composition of the spindles changes from hematite to maghemite, but also the direction of the induced magnetic moment changes from being parallel to the short axis of the spindle to being perpendicular to it. The magnetic dipolar interaction between the particles can be further tuned by adding a screening silica shell. Small-angle X-ray scattering (SAXS) experiments reveal that at high magnetic field, magnetic dipole–dipole interaction forces the silica coated particles to self-assemble into a distorted hexagonal crystal structure at high maghemite content. However, in the case of uncoated maghemite particles, the crystal structure is not very prominent. We interpret this as a consequence of the strong dipolar interaction between uncoated spindles that then become arrested during field-induced self-assembly into a structure riddled with defects. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Nanoscale
volume
9
issue
38
pages
14405 - 14413
publisher
Royal Society of Chemistry
external identifiers
  • scopus:85030630473
  • wos:000412407300013
ISSN
2040-3364
DOI
10.1039/C7NR04518B
language
English
LU publication?
yes
id
2924bb15-f540-4e37-b278-b8177c9a8a8a
date added to LUP
2017-10-04 11:28:15
date last changed
2018-05-06 04:37:10
@article{2924bb15-f540-4e37-b278-b8177c9a8a8a,
  abstract     = {We describe the synthesis of hybrid magnetic ellipsoidal nanoparticles that consist of a mixture of two different iron oxide phases, hematite (α-Fe2O3) and maghemite (γ-Fe2O3), and characterize their magnetic field-driven self-assembly. We demonstrate that the relative amount of the two phases can be adjusted in a continuous way by varying the reaction time during the synthesis, leading to strongly varying magnetic properties of the particles. Not only does the saturation magnetization increase dramatically as the composition of the spindles changes from hematite to maghemite, but also the direction of the induced magnetic moment changes from being parallel to the short axis of the spindle to being perpendicular to it. The magnetic dipolar interaction between the particles can be further tuned by adding a screening silica shell. Small-angle X-ray scattering (SAXS) experiments reveal that at high magnetic field, magnetic dipole–dipole interaction forces the silica coated particles to self-assemble into a distorted hexagonal crystal structure at high maghemite content. However, in the case of uncoated maghemite particles, the crystal structure is not very prominent. We interpret this as a consequence of the strong dipolar interaction between uncoated spindles that then become arrested during field-induced self-assembly into a structure riddled with defects.},
  author       = {Malik, Vikash and Pal, Antara and Pravaz, Olivier and Crassous, Jerome and Granville, Simon and Grobety, Bernard and Hirt, Ann M and Dietsch, Hervé and Schurtenberger, Peter},
  issn         = {2040-3364},
  language     = {eng},
  number       = {38},
  pages        = {14405--14413},
  publisher    = {Royal Society of Chemistry},
  series       = {Nanoscale},
  title        = {Hybrid magnetic iron oxide nanoparticles with tunable field-directed self-assembly},
  url          = {http://dx.doi.org/10.1039/C7NR04518B},
  volume       = {9},
  year         = {2017},
}