uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Influence of cobalt substitution on the magnetic properties of Fe5PB2
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.ORCID iD: 0000-0003-0336-2560
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
Show others and affiliations
2018 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 2, p. 777-784Article in journal (Other academic) Published
Abstract [en]

In this study the effects of cobalt substitutions in Fe5PB2 have been studied. An increased cobalt content reduces the magnetic exchange interactions. This has been concluded from a large, linear decrease in both the Curie temperature as well as the saturated magnetic moment. At high cobalt concentrations, cobalt prefers to order at the M(2) position in the crystal structure. A tunable Curie transition like this shows some prerequisites for magnetic cooling applications.

The substitutional effects of cobalt in (Fe1–xCox)5PB2 have been studied with respect to crystalline structure and chemical order with X-ray diffraction and Mössbauer spectroscopy. The magnetic properties have been determined from magnetic measurements, and density functional theory calculations have been performed for the magnetic properties of both the end compounds, as well as the chemically disordered intermediate compounds. The crystal structure of (Fe1–xCox)5PB2 is tetragonal (space group I4/mcm) with two different metal sites, with a preference for cobalt atoms in the M(2) position (4c) at higher cobalt contents. The substitution also affects the magnetic properties with a decrease of the Curie temperature (TC) with increasing cobalt content, from 622 to 152 K for Fe5PB2 and (Fe0.3Co0.7)5PB2, respectively. Thus, the Curie temperature is dependent on composition, and it is possible to tune TC to a temperature near room temperature, which is one prerequisite for magnetic cooling materials.

Place, publisher, year, edition, pages
2018. Vol. 57, no 2, p. 777-784
National Category
Inorganic Chemistry Condensed Matter Physics Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-331758DOI: 10.1021/acs.inorgchem.7b02663ISI: 000422810900030PubMedID: 29298054OAI: oai:DiVA.org:uu-331758DiVA, id: diva2:1150531
Funder
Swedish Research CouncilSwedish Energy AgencyEuropean Regional Development Fund (ERDF)
Available from: 2017-10-19 Created: 2017-10-19 Last updated: 2018-03-02Bibliographically approved
In thesis
1. Magnetic Materials for Cool Applications: Relations between Structure and Magnetism in Rare Earth Free Alloys
Open this publication in new window or tab >>Magnetic Materials for Cool Applications: Relations between Structure and Magnetism in Rare Earth Free Alloys
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

New and more efficient magnetic materials for energy applications are a big necessity for sustainable future. Whether the application is energy conversion or refrigeration, materials based on sustainable elements should be used, which discards all rare earth elements. For energy conversion, permanent magnets with high magnetisation and working temperature are needed whereas for refrigeration, the entropy difference between the non-magnetised and magnetised states should be large. For this reason, magnetic materials have been synthesised with high temperature methods and structurally and magnetically characterised with the aim of making a material with potential for large scale applications. To really determine the cause of the physical properties the connections between structure (crystalline and magnetic) and, mainly, the magnetic properties have been studied thoroughly.

The materials that have been studied have all been iron based and exhibit properties with potential for the applications in mind. The first system, for permanent magnet applications, was Fe5SiB2. It was found to be unsuitable for a permanent magnet, however, an interesting magnetic behaviour was studied at low temperatures. The magnetic behaviour arose from a change in the magnetic structure which was solved by using neutron diffraction. Substitutions with phosphorus (Fe5Si1-xPxB2) and cobalt (Fe1-xCox)5PB2 were then performed to improve the permanent magnet potential. While the permanent magnetic potential was not improved with cobalt substitutions the magnetic transition temperature could be greatly controlled, a real benefit for magnetic refrigeration. For this purpose AlFe2B2 was also studied, and there it was found, conclusively, that the material undergoes a second order transition, making it unsuitable for magnetic cooling. However, the magnetic structure was solved with two different methods and was found to be ferromagnetic with all magnetic moments aligned along the crystallographic a-direction. Lastly, the origin of magnetic cooling was studied in Fe2P, and can be linked to the interactions between the magnetic and atomic vibrations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. p. 70
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1585
Keyword
Magnetism, Diffraction, X-ray scattering, Neutron Scattering, Permanent magnets, Magnetocalorics
National Category
Organic Chemistry
Research subject
Chemistry with specialization in Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-331762 (URN)978-91-513-0123-5 (ISBN)
Public defence
2017-12-08, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2017-11-16 Created: 2017-10-20 Last updated: 2018-03-07

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textPubMed

Authority records BETA

Cedervall, JohanHedlund, DanielHäggström, LennartEricsson, ToreEdström, AlexanderRusz, JanSvedlindh, PeterGunnarsson, KlasSahlberg, Martin

Search in DiVA

By author/editor
Cedervall, JohanHedlund, DanielHäggström, LennartEricsson, ToreEdström, AlexanderRusz, JanSvedlindh, PeterGunnarsson, KlasSahlberg, Martin
By organisation
Inorganic ChemistryDepartment of Chemistry - ÅngströmSolid State PhysicsMaterials PhysicsMaterials Theory
In the same journal
Inorganic Chemistry
Inorganic ChemistryCondensed Matter PhysicsEngineering and Technology

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 216 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf