Exploring the direct synthesis of exchange-spring nanocomposites by reduction of CoFe2O4 spinel nanoparticles using in situ neutron diffraction

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

Standard

Exploring the direct synthesis of exchange-spring nanocomposites by reduction of CoFe2O4 spinel nanoparticles using in situ neutron diffraction. / Ahlburg, Jakob Voldum; Granados-Miralles, Cecilia; Gjørup, Frederik Holm; Andersen, Henrik Lyder; Christensen, Mogens.

I: Nanoscale, Bind 12, Nr. 17, 2020, s. 9440-9451.

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

Harvard

APA

CBE

MLA

Vancouver

Author

Bibtex

@article{9140e14fc7554e00bf0c8e81213c25fc,
title = "Exploring the direct synthesis of exchange-spring nanocomposites by reduction of CoFe2O4 spinel nanoparticles using in situ neutron diffraction",
abstract = "In situ neutron powder diffraction (NPD) was employed for investigating gram-scale reduction of hard magnetic CoFe2O4 (spinel) nanoparticles into CoFe2O4/CoFe2 exchange-spring nanocomposites via H2 partial reduction. Time-resolved structural information was extracted from Rietveld refinements of the NPD data, revealing significant changes in the reduction kinetics based on the applied temperature and H2 available. The nanocomposite formation was found to take place via the following two-step reduction process: CoxFe3-xO4 → CoyFe1-yO → CozFe2-z. The refined lattice parameters and site occupation fractions indicate that the reduced phases, i.e. CoyFe1-yO and CozFe2-z, initially form as Co-rich compounds (i.e. y > 0.33 and z > 1), which gradually incorporate more Fe as the reduction proceeds. The reduction depletes the Co-content in the parent spinel, which may end up becoming magnetically soft Fe3O4 at high temperature (T = 542 °C), while at lower temperatures there may be a co-existence of Fe3O4 and γ-Fe2O3 or CoxFe3-xO4. The macroscopic magnetic properties of the products were measured by vibrating sample magnetometry (VSM) and revealed the hard and soft magnetic domains in the nanocomposites to be effectively exchange-coupled. An increase of approximately 70% in specific saturation magnetisation, remanence magnetisation, and coercivity compared to the parent CoFe2O4 material was achieved for the best sample.",
author = "Ahlburg, {Jakob Voldum} and Cecilia Granados-Miralles and Gj{\o}rup, {Frederik Holm} and Andersen, {Henrik Lyder} and Mogens Christensen",
year = "2020",
doi = "10.1039/d0nr00912a",
language = "English",
volume = "12",
pages = "9440--9451",
journal = "Nanoscale",
issn = "2040-3364",
publisher = "ROYAL SOC CHEMISTRY",
number = "17",

}

RIS

TY - JOUR

T1 - Exploring the direct synthesis of exchange-spring nanocomposites by reduction of CoFe2O4 spinel nanoparticles using in situ neutron diffraction

AU - Ahlburg, Jakob Voldum

AU - Granados-Miralles, Cecilia

AU - Gjørup, Frederik Holm

AU - Andersen, Henrik Lyder

AU - Christensen, Mogens

PY - 2020

Y1 - 2020

N2 - In situ neutron powder diffraction (NPD) was employed for investigating gram-scale reduction of hard magnetic CoFe2O4 (spinel) nanoparticles into CoFe2O4/CoFe2 exchange-spring nanocomposites via H2 partial reduction. Time-resolved structural information was extracted from Rietveld refinements of the NPD data, revealing significant changes in the reduction kinetics based on the applied temperature and H2 available. The nanocomposite formation was found to take place via the following two-step reduction process: CoxFe3-xO4 → CoyFe1-yO → CozFe2-z. The refined lattice parameters and site occupation fractions indicate that the reduced phases, i.e. CoyFe1-yO and CozFe2-z, initially form as Co-rich compounds (i.e. y > 0.33 and z > 1), which gradually incorporate more Fe as the reduction proceeds. The reduction depletes the Co-content in the parent spinel, which may end up becoming magnetically soft Fe3O4 at high temperature (T = 542 °C), while at lower temperatures there may be a co-existence of Fe3O4 and γ-Fe2O3 or CoxFe3-xO4. The macroscopic magnetic properties of the products were measured by vibrating sample magnetometry (VSM) and revealed the hard and soft magnetic domains in the nanocomposites to be effectively exchange-coupled. An increase of approximately 70% in specific saturation magnetisation, remanence magnetisation, and coercivity compared to the parent CoFe2O4 material was achieved for the best sample.

AB - In situ neutron powder diffraction (NPD) was employed for investigating gram-scale reduction of hard magnetic CoFe2O4 (spinel) nanoparticles into CoFe2O4/CoFe2 exchange-spring nanocomposites via H2 partial reduction. Time-resolved structural information was extracted from Rietveld refinements of the NPD data, revealing significant changes in the reduction kinetics based on the applied temperature and H2 available. The nanocomposite formation was found to take place via the following two-step reduction process: CoxFe3-xO4 → CoyFe1-yO → CozFe2-z. The refined lattice parameters and site occupation fractions indicate that the reduced phases, i.e. CoyFe1-yO and CozFe2-z, initially form as Co-rich compounds (i.e. y > 0.33 and z > 1), which gradually incorporate more Fe as the reduction proceeds. The reduction depletes the Co-content in the parent spinel, which may end up becoming magnetically soft Fe3O4 at high temperature (T = 542 °C), while at lower temperatures there may be a co-existence of Fe3O4 and γ-Fe2O3 or CoxFe3-xO4. The macroscopic magnetic properties of the products were measured by vibrating sample magnetometry (VSM) and revealed the hard and soft magnetic domains in the nanocomposites to be effectively exchange-coupled. An increase of approximately 70% in specific saturation magnetisation, remanence magnetisation, and coercivity compared to the parent CoFe2O4 material was achieved for the best sample.

UR - http://www.scopus.com/inward/record.url?scp=85084720585&partnerID=8YFLogxK

U2 - 10.1039/d0nr00912a

DO - 10.1039/d0nr00912a

M3 - Journal article

C2 - 32324188

AN - SCOPUS:85084720585

VL - 12

SP - 9440

EP - 9451

JO - Nanoscale

JF - Nanoscale

SN - 2040-3364

IS - 17

ER -