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 L.; Christensen, Mogens

doi:10.1039/d0nr00912a

Cited by 7 publications

(13 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For part 2, the CoFe 2 O 4 powders were prepared using the method described by Ahlburg et al (2020). Two autoclave syntheses similar to the method described in part 1 were used with the exception of the usage of higher reagent concentrations of 3.0 M Co(NO 3 ) 2 Á6H 2 O and 2.3 M Fe(NO 3 ) 3 Á9H 2 O, but still with a 1:2 Co:Fe ratio and an OH À :NO 3 À molar ratio of 1.25:1 when adding NaOH.…”

Section: Sample Preparationmentioning

confidence: 99%

“…The present study is based on a compilation of data from three of our earlier studies on CoFe 2 O 4 nanoparticles (Granados-Miralles et al, 2018;Ahlburg et al, 2020;Stingaciu et al, 2017), as well as previously unpublished data. The X-ray and neutron diffraction patterns stem from several different CoFe 2 O 4 samples and have been collected using both Co and Cu in-house X-ray diffractometers, as well as various NPD instruments.…”

mentioning

confidence: 99%

See 1 more Smart Citation

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data

Henry¹,

Ahlburg²,

Andersen³

et al. 2022

J Appl Cryst

Self Cite

View full text Add to dashboard Cite

Powder X-ray diffraction (PXRD) and neutron powder diffraction (NPD) have been used to investigate the crystal structure of CoFe2O4 nanoparticles prepared via different hydrothermal synthesis routes, with particular attention given to accurately determining the spinel inversion degrees. The study is divided into four parts. In the first part, the investigations focus on the influence of using different diffraction pattern combinations (NPD, Cu-source PXRD and Co-source PXRD) for the structural modelling. It is found that combining PXRD data from a Co source with NPD data offers a robust structural model. The second part of the study evaluates the reproducibility of the employed multipattern Rietveld refinement procedure using different data sets collected on the same sample, as well as on equivalently prepared samples. The refinement procedure gives reproducible results and reveals that the synthesis method is likewise reproducible since only minor differences are noted between the samples. The third part focuses on the structural consequences of (i) the employed heating rate (achieved using three different hydrothermal reactor types) and (ii) changing the cobalt salt in the precursors [aqueous salt solutions of Co(CH3COOH)2, Co(NO3)2 and CoCl2] in the synthesis. It is found that increasing the heating rate causes a change in the crystal structure (unit cell and crystallite sizes) while the Co/Fe occupancy and magnetic parameters remain similar in all cases. Also, changing the type of cobalt salt does not alter the final crystal/magnetic structure of the CoFe2O4 nanoparticles. The last part of this study is a consideration of the chemicals and parameters used in the synthesis of the different samples. All the presented samples exhibit a similar crystal and magnetic structure, with only minor deviations. It is also evident that the refinement method used played a key role in the description of the sample.

show abstract

Section: Sample Preparationmentioning

confidence: 99%

mentioning

confidence: 99%

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data

Henry¹,

Ahlburg²,

Andersen³

et al. 2022

J Appl Cryst

Self Cite

View full text Add to dashboard Cite

show abstract

“…Such behavior is observed for example in DyFe 2 /YFe 2 or Fe/FePt . Exchange-spring behavior has also been reported in CoFe 2 O 4 /CoFe 2 nanoparticles , and ultrathin bilayers . This material system has the substantial advantage to be free from rare earth or noble metals and instead relies on the more widely available transition metals Fe and Co. Also the all-oxide material system Fe 3 O 4 /CoFe 2 O 4 exchange-spring behavior has been investigated in nanocomposites and epitaxial bilayers. , Moreover, the possibility of electric field control of exchange-spring behavior has been reported .…”

Section: Introductionmentioning

confidence: 99%

Inferface Magnetization Phenomena in Epitaxial Thin Fe₃O₄/Co_xFe_3–xO₄ Bilayers

et al. 2021

View full text Add to dashboard Cite

In this work, we present a study about the chemical and magnetic properties of thin magnetite/cobalt ferrite bilayers deposited on MgO(001). Two series of samples with different Co x Fe 3−x O 4 stoichiometries (x = 1 and x = 0.5) in combination with Fe 3 O 4 layers of varying thickness were prepared by reactive molecular beam epitaxy. The quality of the respective films were controlled by means of in situ Xray photelectron spectroscopy and low energy electron diffraction. Stoichiometry and electronic structure were carried out by hard X-ray photoelectron spectroscopy. To determine the cationic distribution and magnetic moments, X-ray magnetic circular dichroism measurements were performed and charge transfer multiplet and sum rule calculations were applied. Here we find an enhanced interface magnetization for the bilayers. Additionally, superconducting quantum interference device measurements showed characteristic exchange-spring behavior.

show abstract

“…Consequently, the improvement and successful miniaturization of functional devices is highly dependent on improving the properties of the magnetic materials used, while limiting the production complexity and cost. 4 Unfortunately, even though magnetic compounds are crucial in our society and are being researched heavily, the classical curriculum in high school chemistry or physics does not include any synthesis of magnetic materials and rarely investigates the properties of any synthesized compounds. This is in many cases due to a lack of proper laboratory equipment, in particular when it comes to measuring the magnetic properties of a material.…”

Section: ■ Introduction and Backgroundmentioning

confidence: 99%

“…In many cases, the device performance is strongly dependent on the incorporated magnetic compound. Consequently, the improvement and successful miniaturization of functional devices is highly dependent on improving the properties of the magnetic materials used, while limiting the production complexity and cost . Unfortunately, even though magnetic compounds are crucial in our society and are being researched heavily, the classical curriculum in high school chemistry or physics does not include any synthesis of magnetic materials and rarely investigates the properties of any synthesized compounds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of a Magnetic Ceramic Using an Easily Accessible Scale Setup

et al. 2021

Self Cite

View full text Add to dashboard Cite

In this experiment, students explore the synthesis and physical property characterization of the magnetic material strontium hexaferrite (SrFe 12 O 19 ). SrFe 12 O 19 crystallites are prepared by a simple but fascinating sol−gel autocombustion synthesis. The prepared powder is compacted into pellets and sintered. With variation of the sintering temperature, it is possible to modify the magnetic properties. The structural properties of the samples are analyzed by powder X-ray diffraction. A tutorial demonstrates for the students how powder X-ray diffraction data from the sample combined with Rietveld refinement can extract phase purity and crystallite size. The magnetic properties are measured using a simple setup with a scale and a strong neodymium magnet; this gives an intuitive understanding of magnetism and how to measure magnetic properties. Additionally, the magnetic properties are measured with a vibrating sample magnetometer and compared to the results obtained using the simple scale method. The lab exercise can be adapted to different levels of education based on the background of the students and the equipment available in the laboratory.

show abstract

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.

Cited by 7 publications

References 62 publications

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data

Inferface Magnetization Phenomena in Epitaxial Thin Fe₃O₄/Co_xFe_3–xO₄ Bilayers

Synthesis and Characterization of a Magnetic Ceramic Using an Easily Accessible Scale Setup

Contact Info

Product

Resources

About

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.

Cited by 7 publications

References 62 publications

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data

Inferface Magnetization Phenomena in Epitaxial Thin Fe3O4/CoxFe3–xO4 Bilayers

Synthesis and Characterization of a Magnetic Ceramic Using an Easily Accessible Scale Setup

Contact Info

Product

Resources

About

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

Inferface Magnetization Phenomena in Epitaxial Thin Fe₃O₄/Co_xFe_3–xO₄ Bilayers