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
Irreversible structure change of the as prepared FeMnP1−xSix-structure on the initial cooling through the curie temperature
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Show others and affiliations
2015 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 374, 455-458 p.Article in journal (Refereed) Published
Abstract [en]

FeMnP0.75Si0.25 experiences a first order para- to ferromagnetic transition at about 200 K. In common with some other alloy compositions crystallizing in the Fe2P structure, the magnetic transition of the as prepared alloy occurs at a lower temperature than on subsequent cooling events. This virgin effect is found to be accompanied by a magnetostrictively induced irreversible structure change that persists on succeeding cooling heating cycles. These findings provide means to understand and control the thermal hysteresis of the (Fe1-xMnx)(2)P1-ySiy alloy system which is a promising material class for use in magnetocaloric refrigerators.

Place, publisher, year, edition, pages
2015. Vol. 374, 455-458 p.
Keyword [en]
FeMnP0.75Si0.25, First order ferromagnetic transition, Thermal hysteresis, Virgin effect, X-ray powder diffraction, Magnetocalorics
National Category
Inorganic Chemistry Engineering and Technology
Research subject
Chemistry with specialization in Inorganic Chemistry; Engineering Science with specialization in Solid State Physics
Identifiers
URN: urn:nbn:se:uu:diva-233462DOI: 10.1016/j.jmmm.2014.08.088ISI: 000344949000073OAI: oai:DiVA.org:uu-233462DiVA: diva2:753308
Funder
Swedish Research Council
Available from: 2014-10-07 Created: 2014-10-06 Last updated: 2017-12-05Bibliographically approved
In thesis
1. Structure-Magnetic Relationships in the Fe-Mn-P-Si System for Energy Applications
Open this publication in new window or tab >>Structure-Magnetic Relationships in the Fe-Mn-P-Si System for Energy Applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Demands for new, energy-efficient appliances have greatly increased in response to our growing need for a more environmentally friendly society. Magnetic refrigeration is a technique that utilizes the magnetocaloric effect, with possible energy savings of up to 30% compared to commercial gas compression refrigerators. A material appropriate for commercial magnetocaloric devices should be both cheap and non-toxic; it should also exhibit a first-order magnetic transitions close to room temperature. The magnetic properties of Fe2P-related materials can be relevant in this context, since their magnetic properties can be finely tuned through the substitution of Fe by Mn and P by Si, As, Ge or B to meet the general requirements for a magnetocaloric device.

An in-depth study has therefore here been made of the structural and magnetic properties of the (Fe,Mn)2(P,Si)-system. The phase diagram of the FeMnP1-xSix-system has been carefully re-examined. It is found to contain two single-phase regions: an orthorhombic Co2P-type structure (x < 0.15) and a hexagonal Fe2P-type structure (0.24 ≤ x < 0.50). Selected compounds within the Fe2P-type region of the phase diagram have been shown to exhibit potential for use in magnetic refrigeration applications.

Neutron powder diffraction has here been used to determine the magnetic structures of selected crystalline compositions within the FeMnP1-xSix-system to gain a better understanding of its magnetic properties. The Fe2P-type region is mainly ferromagnetic, but an incommensurate antiferromagnetic structure has also been identified close to the Co2P/Fe2P-type phase border for x ≈ 0.25.

The so-called ''virgin effect'' in the Fe2P-type region of the FeMn(P,Si) phase diagram is found to be accompanied by an irreversible structural phase transition induced by magnetostriction. This new phase is found to be preserved during successive cooling-heating cycles. Furthermore, the magnetic properties of the substituted Fe2P-type structure changes significantly for metal:non-metal ratios away from 2:1. Such deviations could well explain the apparently conflicting structure-property relationships described in earlier literature for the FeMnP1-xSix-system.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 74 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1197
Keyword
Magnetocaloric, X-ray powder diffraction, Neutron powder diffraction, Magnetization measurements, Phase diagram, Crystal structure, Magnetic structure, Incommensurate structure, Ferromagnetic, Antiferromagnetic, Fe2P, Fe-Mn-P-Si.
National Category
Inorganic Chemistry
Research subject
Chemistry with specialization in Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-234516 (URN)978-91-554-9091-1 (ISBN)
Public defence
2014-12-12, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2014-11-20 Created: 2014-10-20 Last updated: 2015-02-03
2. Structure-Magnetism Relations in Selected Iron-based Alloys: A New Base for Rare Earth Free Magnetic Materials
Open this publication in new window or tab >>Structure-Magnetism Relations in Selected Iron-based Alloys: A New Base for Rare Earth Free Magnetic Materials
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Materials for energy applications are of great importance for a sustainable future society. Among these, stronger, lighter and more efficient magnetic materials will be able to aid mankind in many applications for energy conversion, for example generators for energy production, electric vehicles and magnetic refrigerators. Another requirement for the materials is that they should be made from cheap and abundant elements. For these reasons temperature induced magnetic transitions for three materials were studied in this work; one for permanent magnet applications and two magnetocaloric materials.

Fe5SiB2 has a high Curie temperature and orders ferromagnetically at 760 K, providing possible application as a permanent magnet material. The ordering of the magnetic moments were studied and found to be aligned along the tetragonal c-axis and Fe5SiB2 undergoes a spin transition on cooling through a transition temperature (172 K), where the spins reorient along the a-axis in an easy plane.

AlFe2B2 orders ferromagnetically at 285 K, making it a candidate for the active material in a magnetic refrigerator. The order of the magnetic transition has been studied as well as the magnetic structure. It was found that the magnetic moments are aligned along the crystallographic a-axis and that the magnetic transition is of second order.

FeMnP0.75Si0.25 undergoes a first order magnetic transition around 200 K and the transition temperatures on cooling are different for the first cooling/heating cycle than for following cycles. This so called ”virgin effect” has been studied and found to originate from an irreversible structure change on the first cooling cycle through the ferromagnetic transition temperature.

Place, publisher, year, edition, pages
Uppsala: Kph Trycksaksbolaget: Kph, 2015. 47 p.
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-267575 (URN)
Presentation
2015-12-17, 09:15 (English)
Opponent
Supervisors
Available from: 2015-12-02 Created: 2015-11-24 Last updated: 2015-12-02Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Höglin, ViktorCedervall, JohanAndersson, Mikael SvanteSarkar, TapatiNordblad, PerSahlberg, Martin

Search in DiVA

By author/editor
Höglin, ViktorCedervall, JohanAndersson, Mikael SvanteSarkar, TapatiNordblad, PerSahlberg, Martin
By organisation
Inorganic ChemistrySolid State Physics
In the same journal
Journal of Magnetism and Magnetic Materials
Inorganic ChemistryEngineering and Technology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 1395 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