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Detailed study of the magnetic ordering in FeMnP0.75Si0.25
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. ICT Materials Physics, KTH Royal Institute of Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Fundamental Aspects of Materials and Energy, Faculty of Applied Sciences, TUDelft.
Nuclear Physics Institute, Academy of Sciences of the Czech Republic.
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2015 (English)In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 221, 240-246 p.Article in journal (Refereed) Published
Abstract [en]

Magnetic and crystallographic properties of FeMnP0.75Si0.25 in the hexagonal Fe2P-type structure have been investigated by X-ray powder diffraction, neutron powder diffraction and magnetic measurements. The room temperature diffractograms reveal co-existence of two distinct structural phases in the samples with small, but significant, differences only in the unit cell dimensions. The volume ratio between the two phases is governed by the annealing conditions. One of the phases orders ferromagnetically (TC = 250 K) and the other in an incommensurate antiferromagnetic structure at low temperatures (qx = 0.363(1), TN = 150 K).

Place, publisher, year, edition, pages
2015. Vol. 221, 240-246 p.
Keyword [en]
Magnetic structure, Incommensurate ordering, Neutron powder diffraction, X-ray powder diffraction (XRD), Magnetization
National Category
Inorganic Chemistry Engineering and Technology
Research subject
Chemistry with specialization in Inorganic Chemistry; Engineering Science with specialization in Solid State Physics
URN: urn:nbn:se:uu:diva-234509DOI: 10.1016/j.jssc.2014.10.013ISI: 000347263700034OAI: oai:DiVA.org:uu-234509DiVA: diva2:756855
Available from: 2014-10-20 Created: 2014-10-20 Last updated: 2016-04-22Bibliographically 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.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1197
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
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)
Available from: 2014-11-20 Created: 2014-10-20 Last updated: 2015-02-03

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Höglin, ViktorHudl, MatthiasCaron, LuanaNordblad, PerAndersson, YvonneSahlberg, Martin
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