Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion

Henrik Lyder Andersen, Cecilia Granados-Miralles, Matilde Saura-Múzquiz, Marian Stingaciu, Jacob Larsen, Frederik Søndergaard-Pedersen, Jakob Voldum Ahlburg, Lukas Keller, Cathrine Frandsen, Mogens Christensen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The magnetic properties of spinel ferrites (MFe2O4, M = Mn, Fe, Co, Ni, Zn, etc.) are largely determined by the type of divalent cation, M2+ and cation distribution between the tetrahedral and octahedral sites in the structure. Partial substitution of Zn2+ into the thermodynamically preferred tetrahedral coordination in ferrites produces an increase in magnetic saturation at room temperature. However, nanosized crystallites are known to adopt different structures compared to their bulk equivalents. Consequently, reliable characterization of the atomic structure of nanosized ferrites is essential for understanding and tailoring their magnetic properties. Here, we present a meticulous study of the crystal-, magnetic- and micro-structures of mixed ZnxCo1−xFe2O4 spinel ferrite nanocrystallites in the entire composition range (x = 0.0–1.0 in steps of 0.1). Gram-scale nanoparticle preparation was performed via the widely used hydrothermal method. Eight compositions were selected to study the effect of 4 hours vacuum annealing at 823 K. Combined Rietveld refinement of powder X-ray and neutron diffraction data along with Mössbauer analysis reveal how the as-synthesized nanocrystallites adopt metastable cation inversions, different from the well-established and thermodynamically stable inversions of the bulk equivalents. The annealing treatment causes the structure of the crystallites to relax towards a more bulk-like cation distribution. For all compositions, the smaller as-synthesized nanocrystallites with metastable cation inversion exhibit a higher saturation magnetization compared to the annealed samples. The demonstrated control over the spinel ferrite cation distribution is a key step on the way to designing cheap magnetic materials with tunable properties optimized for specific applications.
Original languageEnglish
JournalMaterials Chemistry Frontiers
Volume3
Issue number4
Pages (from-to)668-679
Number of pages12
ISSN2052-1537
DOIs
Publication statusPublished - 2019

Cite this

Andersen, H. L., Granados-Miralles, C., Saura-Múzquiz, M., Stingaciu, M., Larsen, J., Søndergaard-Pedersen, F., ... Christensen, M. (2019). Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion. Materials Chemistry Frontiers, 3(4), 668-679. https://doi.org/10.1039/C9QM00012G
Andersen, Henrik Lyder ; Granados-Miralles, Cecilia ; Saura-Múzquiz, Matilde ; Stingaciu, Marian ; Larsen, Jacob ; Søndergaard-Pedersen, Frederik ; Ahlburg, Jakob Voldum ; Keller, Lukas ; Frandsen, Cathrine ; Christensen, Mogens. / Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion. In: Materials Chemistry Frontiers. 2019 ; Vol. 3, No. 4. pp. 668-679.
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title = "Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion",
abstract = "The magnetic properties of spinel ferrites (MFe2O4, M = Mn, Fe, Co, Ni, Zn, etc.) are largely determined by the type of divalent cation, M2+ and cation distribution between the tetrahedral and octahedral sites in the structure. Partial substitution of Zn2+ into the thermodynamically preferred tetrahedral coordination in ferrites produces an increase in magnetic saturation at room temperature. However, nanosized crystallites are known to adopt different structures compared to their bulk equivalents. Consequently, reliable characterization of the atomic structure of nanosized ferrites is essential for understanding and tailoring their magnetic properties. Here, we present a meticulous study of the crystal-, magnetic- and micro-structures of mixed ZnxCo1−xFe2O4 spinel ferrite nanocrystallites in the entire composition range (x = 0.0–1.0 in steps of 0.1). Gram-scale nanoparticle preparation was performed via the widely used hydrothermal method. Eight compositions were selected to study the effect of 4 hours vacuum annealing at 823 K. Combined Rietveld refinement of powder X-ray and neutron diffraction data along with M{\"o}ssbauer analysis reveal how the as-synthesized nanocrystallites adopt metastable cation inversions, different from the well-established and thermodynamically stable inversions of the bulk equivalents. The annealing treatment causes the structure of the crystallites to relax towards a more bulk-like cation distribution. For all compositions, the smaller as-synthesized nanocrystallites with metastable cation inversion exhibit a higher saturation magnetization compared to the annealed samples. The demonstrated control over the spinel ferrite cation distribution is a key step on the way to designing cheap magnetic materials with tunable properties optimized for specific applications.",
author = "Andersen, {Henrik Lyder} and Cecilia Granados-Miralles and Matilde Saura-M{\'u}zquiz and Marian Stingaciu and Jacob Larsen and Frederik S{\o}ndergaard-Pedersen and Ahlburg, {Jakob Voldum} and Lukas Keller and Cathrine Frandsen and Mogens Christensen",
year = "2019",
doi = "10.1039/C9QM00012G",
language = "English",
volume = "3",
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Andersen, HL, Granados-Miralles, C, Saura-Múzquiz, M, Stingaciu, M, Larsen, J, Søndergaard-Pedersen, F, Ahlburg, JV, Keller, L, Frandsen, C & Christensen, M 2019, 'Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion', Materials Chemistry Frontiers, vol. 3, no. 4, pp. 668-679. https://doi.org/10.1039/C9QM00012G

Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion. / Andersen, Henrik Lyder; Granados-Miralles, Cecilia; Saura-Múzquiz, Matilde; Stingaciu, Marian; Larsen, Jacob; Søndergaard-Pedersen, Frederik; Ahlburg, Jakob Voldum; Keller, Lukas; Frandsen, Cathrine; Christensen, Mogens.

In: Materials Chemistry Frontiers, Vol. 3, No. 4, 2019, p. 668-679.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion

AU - Andersen, Henrik Lyder

AU - Granados-Miralles, Cecilia

AU - Saura-Múzquiz, Matilde

AU - Stingaciu, Marian

AU - Larsen, Jacob

AU - Søndergaard-Pedersen, Frederik

AU - Ahlburg, Jakob Voldum

AU - Keller, Lukas

AU - Frandsen, Cathrine

AU - Christensen, Mogens

PY - 2019

Y1 - 2019

N2 - The magnetic properties of spinel ferrites (MFe2O4, M = Mn, Fe, Co, Ni, Zn, etc.) are largely determined by the type of divalent cation, M2+ and cation distribution between the tetrahedral and octahedral sites in the structure. Partial substitution of Zn2+ into the thermodynamically preferred tetrahedral coordination in ferrites produces an increase in magnetic saturation at room temperature. However, nanosized crystallites are known to adopt different structures compared to their bulk equivalents. Consequently, reliable characterization of the atomic structure of nanosized ferrites is essential for understanding and tailoring their magnetic properties. Here, we present a meticulous study of the crystal-, magnetic- and micro-structures of mixed ZnxCo1−xFe2O4 spinel ferrite nanocrystallites in the entire composition range (x = 0.0–1.0 in steps of 0.1). Gram-scale nanoparticle preparation was performed via the widely used hydrothermal method. Eight compositions were selected to study the effect of 4 hours vacuum annealing at 823 K. Combined Rietveld refinement of powder X-ray and neutron diffraction data along with Mössbauer analysis reveal how the as-synthesized nanocrystallites adopt metastable cation inversions, different from the well-established and thermodynamically stable inversions of the bulk equivalents. The annealing treatment causes the structure of the crystallites to relax towards a more bulk-like cation distribution. For all compositions, the smaller as-synthesized nanocrystallites with metastable cation inversion exhibit a higher saturation magnetization compared to the annealed samples. The demonstrated control over the spinel ferrite cation distribution is a key step on the way to designing cheap magnetic materials with tunable properties optimized for specific applications.

AB - The magnetic properties of spinel ferrites (MFe2O4, M = Mn, Fe, Co, Ni, Zn, etc.) are largely determined by the type of divalent cation, M2+ and cation distribution between the tetrahedral and octahedral sites in the structure. Partial substitution of Zn2+ into the thermodynamically preferred tetrahedral coordination in ferrites produces an increase in magnetic saturation at room temperature. However, nanosized crystallites are known to adopt different structures compared to their bulk equivalents. Consequently, reliable characterization of the atomic structure of nanosized ferrites is essential for understanding and tailoring their magnetic properties. Here, we present a meticulous study of the crystal-, magnetic- and micro-structures of mixed ZnxCo1−xFe2O4 spinel ferrite nanocrystallites in the entire composition range (x = 0.0–1.0 in steps of 0.1). Gram-scale nanoparticle preparation was performed via the widely used hydrothermal method. Eight compositions were selected to study the effect of 4 hours vacuum annealing at 823 K. Combined Rietveld refinement of powder X-ray and neutron diffraction data along with Mössbauer analysis reveal how the as-synthesized nanocrystallites adopt metastable cation inversions, different from the well-established and thermodynamically stable inversions of the bulk equivalents. The annealing treatment causes the structure of the crystallites to relax towards a more bulk-like cation distribution. For all compositions, the smaller as-synthesized nanocrystallites with metastable cation inversion exhibit a higher saturation magnetization compared to the annealed samples. The demonstrated control over the spinel ferrite cation distribution is a key step on the way to designing cheap magnetic materials with tunable properties optimized for specific applications.

U2 - 10.1039/C9QM00012G

DO - 10.1039/C9QM00012G

M3 - Journal article

VL - 3

SP - 668

EP - 679

JO - Materials Chemistry Frontiers

JF - Materials Chemistry Frontiers

SN - 2052-1537

IS - 4

ER -

Andersen HL, Granados-Miralles C, Saura-Múzquiz M, Stingaciu M, Larsen J, Søndergaard-Pedersen F et al. Enhanced intrinsic saturation magnetization of ZnxCo1−xFe2O4 nanocrystallites with metastable spinel inversion. Materials Chemistry Frontiers. 2019;3(4):668-679. https://doi.org/10.1039/C9QM00012G