Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets

Cecilia Granados-Miralles, Matilde Saura-Muzquiz, Henrik L. Andersen, Adrian Quesada, Jakob V. Ahlburg, Ann-Christin Dippel, Emmanuel Canevet, Mogens Christensen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

During the past decade, CoFe2O4 (hard)/Co Fe alloy (soft) magnetic nanocomposites have been routinely prepared by partial reduction of CoFe2O4 nanoparticles. Monoxide (i.e., FeO or CoO) has often been detected as a byproduct of the reduction, although it remains unclear whether the formation of this phase occurs during the reduction itself or at a later stage. Here, a novel reaction cell was designed to monitor the reduction in situ using synchrotron powder X-ray diffraction (PXRD). Sequential Rietveld refinements of the in situ data yielded time-resolved information on the sample composition and confirmed that the monoxide is generated as an intermediate phase. The macroscopic magnetic properties of samples at different reduction stages were measured by means of vibrating sample magnetometry (VSM), revealing a magnetic softening with increasing soft phase content, which was too pronounced to be exclusively explained by the introduction of soft material in the system. The elemental compositions of the constituent phases were obtained from joint Rietveld refinements of ex situ high resolution PXRD and neutron powder diffraction (NPD) data. It was found that the alloy has a tendency to emerge in a Co-rich form, inducing a Co deficiency on the remaining spinel phase, which can explain the early softening of the magnetic material.

Original languageEnglish
JournalACS Applied Nano Materials
Volume1
Issue number7
Pages (from-to)3693-3704
Number of pages23
ISSN2574-0970
DOIs
Publication statusPublished - 2018

Keywords

  • Nanocomposite
  • Ferrite
  • Permanent magnet
  • Exchange-coupling
  • In Situ
  • Neutron powder diffraction
  • Elemental composition
  • Rietvield refinement

Cite this

Granados-Miralles, C., Saura-Muzquiz, M., Andersen, H. L., Quesada, A., Ahlburg, J. V., Dippel, A-C., ... Christensen, M. (2018). Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets. ACS Applied Nano Materials , 1(7), 3693-3704. https://doi.org/10.1021/acsanm.8b00808
Granados-Miralles, Cecilia ; Saura-Muzquiz, Matilde ; Andersen, Henrik L. ; Quesada, Adrian ; Ahlburg, Jakob V. ; Dippel, Ann-Christin ; Canevet, Emmanuel ; Christensen, Mogens. / Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets. In: ACS Applied Nano Materials . 2018 ; Vol. 1, No. 7. pp. 3693-3704.
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title = "Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets",
abstract = "During the past decade, CoFe2O4 (hard)/Co Fe alloy (soft) magnetic nanocomposites have been routinely prepared by partial reduction of CoFe2O4 nanoparticles. Monoxide (i.e., FeO or CoO) has often been detected as a byproduct of the reduction, although it remains unclear whether the formation of this phase occurs during the reduction itself or at a later stage. Here, a novel reaction cell was designed to monitor the reduction in situ using synchrotron powder X-ray diffraction (PXRD). Sequential Rietveld refinements of the in situ data yielded time-resolved information on the sample composition and confirmed that the monoxide is generated as an intermediate phase. The macroscopic magnetic properties of samples at different reduction stages were measured by means of vibrating sample magnetometry (VSM), revealing a magnetic softening with increasing soft phase content, which was too pronounced to be exclusively explained by the introduction of soft material in the system. The elemental compositions of the constituent phases were obtained from joint Rietveld refinements of ex situ high resolution PXRD and neutron powder diffraction (NPD) data. It was found that the alloy has a tendency to emerge in a Co-rich form, inducing a Co deficiency on the remaining spinel phase, which can explain the early softening of the magnetic material.",
keywords = "Nanocomposite, Ferrite, Permanent magnet, Exchange-coupling, In Situ, Neutron powder diffraction, Elemental composition, Rietvield refinement",
author = "Cecilia Granados-Miralles and Matilde Saura-Muzquiz and Andersen, {Henrik L.} and Adrian Quesada and Ahlburg, {Jakob V.} and Ann-Christin Dippel and Emmanuel Canevet and Mogens Christensen",
year = "2018",
doi = "10.1021/acsanm.8b00808",
language = "English",
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pages = "3693--3704",
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Granados-Miralles, C, Saura-Muzquiz, M, Andersen, HL, Quesada, A, Ahlburg, JV, Dippel, A-C, Canevet, E & Christensen, M 2018, 'Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets', ACS Applied Nano Materials , vol. 1, no. 7, pp. 3693-3704. https://doi.org/10.1021/acsanm.8b00808

Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets. / Granados-Miralles, Cecilia; Saura-Muzquiz, Matilde; Andersen, Henrik L.; Quesada, Adrian; Ahlburg, Jakob V.; Dippel, Ann-Christin; Canevet, Emmanuel; Christensen, Mogens.

In: ACS Applied Nano Materials , Vol. 1, No. 7, 2018, p. 3693-3704.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets

AU - Granados-Miralles, Cecilia

AU - Saura-Muzquiz, Matilde

AU - Andersen, Henrik L.

AU - Quesada, Adrian

AU - Ahlburg, Jakob V.

AU - Dippel, Ann-Christin

AU - Canevet, Emmanuel

AU - Christensen, Mogens

PY - 2018

Y1 - 2018

N2 - During the past decade, CoFe2O4 (hard)/Co Fe alloy (soft) magnetic nanocomposites have been routinely prepared by partial reduction of CoFe2O4 nanoparticles. Monoxide (i.e., FeO or CoO) has often been detected as a byproduct of the reduction, although it remains unclear whether the formation of this phase occurs during the reduction itself or at a later stage. Here, a novel reaction cell was designed to monitor the reduction in situ using synchrotron powder X-ray diffraction (PXRD). Sequential Rietveld refinements of the in situ data yielded time-resolved information on the sample composition and confirmed that the monoxide is generated as an intermediate phase. The macroscopic magnetic properties of samples at different reduction stages were measured by means of vibrating sample magnetometry (VSM), revealing a magnetic softening with increasing soft phase content, which was too pronounced to be exclusively explained by the introduction of soft material in the system. The elemental compositions of the constituent phases were obtained from joint Rietveld refinements of ex situ high resolution PXRD and neutron powder diffraction (NPD) data. It was found that the alloy has a tendency to emerge in a Co-rich form, inducing a Co deficiency on the remaining spinel phase, which can explain the early softening of the magnetic material.

AB - During the past decade, CoFe2O4 (hard)/Co Fe alloy (soft) magnetic nanocomposites have been routinely prepared by partial reduction of CoFe2O4 nanoparticles. Monoxide (i.e., FeO or CoO) has often been detected as a byproduct of the reduction, although it remains unclear whether the formation of this phase occurs during the reduction itself or at a later stage. Here, a novel reaction cell was designed to monitor the reduction in situ using synchrotron powder X-ray diffraction (PXRD). Sequential Rietveld refinements of the in situ data yielded time-resolved information on the sample composition and confirmed that the monoxide is generated as an intermediate phase. The macroscopic magnetic properties of samples at different reduction stages were measured by means of vibrating sample magnetometry (VSM), revealing a magnetic softening with increasing soft phase content, which was too pronounced to be exclusively explained by the introduction of soft material in the system. The elemental compositions of the constituent phases were obtained from joint Rietveld refinements of ex situ high resolution PXRD and neutron powder diffraction (NPD) data. It was found that the alloy has a tendency to emerge in a Co-rich form, inducing a Co deficiency on the remaining spinel phase, which can explain the early softening of the magnetic material.

KW - Nanocomposite

KW - Ferrite

KW - Permanent magnet

KW - Exchange-coupling

KW - In Situ

KW - Neutron powder diffraction

KW - Elemental composition

KW - Rietvield refinement

U2 - 10.1021/acsanm.8b00808

DO - 10.1021/acsanm.8b00808

M3 - Journal article

VL - 1

SP - 3693

EP - 3704

JO - ACS Applied Nano Materials

JF - ACS Applied Nano Materials

SN - 2574-0970

IS - 7

ER -

Granados-Miralles C, Saura-Muzquiz M, Andersen HL, Quesada A, Ahlburg JV, Dippel A-C et al. Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent Magnets. ACS Applied Nano Materials . 2018;1(7):3693-3704. https://doi.org/10.1021/acsanm.8b00808