Gottschall, Tino ; Skokov, Konstantin P. ; Burriel, Ramon ; Gutfleisch, Oliver (2016)
On the S(T) diagram of magnetocaloric materials with first-order transition: Kinetic and cyclic effects of Heusler alloys.
In: Acta Materialia, 107
doi: 10.1016/j.actamat.2016.01.052
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
For magnetocaloric materials the total entropy diagram S(T) in different magnetic fields is of central importance. From such a plot the isothermal entropy change Delta S-T and the adiabatic temperature change Delta T-ad can be well-defined. Aim of this work is to investigate the reversible magnetocaloric effect of Heusler alloys under cycling in terms of the S(T) diagram. For this purpose we selected three different Heusler alloys of Ni-Mn-In with transition temperatures between 200 k and room temperature. The S(T) diagrams of the three materials cover all conceivable shapes and are therefore representative for inverse magnetocaloric Heusler alloys. First we comprehensively analyzed the magnetocaloric properties of this model system using calorimetry, magnetometry and direct measurements of the adiabatic temperature change Delta T-ad and subsequently combined those results into the S(T) diagram. It turns out that under certain measurement conditions significant discrepancies can appear. With the help of in-situ optical microscopy, this effect could be attributed to kinetic relaxation effects in the pure martensite phase before the actual Delta T-ad experiment. Furthermore we found that the S(T) diagram obtained under continuous heating and cooling fails to describe the reversible magnetocaloric properties of minor loops under cycling. Utilizing cyclic measurements of the adiabatic temperature change together with calorimetric data it is however possible to determine the reversible magnetic field induced entropy change Delta S-T in fast operation comparable to real device conditions which can be applied to every magnetocaloric material with a first-order transition. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2016 |
| Autor(en): | Gottschall, Tino ; Skokov, Konstantin P. ; Burriel, Ramon ; Gutfleisch, Oliver |
| Art des Eintrags: | Bibliographie |
| Titel: | On the S(T) diagram of magnetocaloric materials with first-order transition: Kinetic and cyclic effects of Heusler alloys |
| Sprache: | Englisch |
| Publikationsjahr: | 1 April 2016 |
| Verlag: | PERGAMON-ELSEVIER SCIENCE LTD |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Acta Materialia |
| Jahrgang/Volume einer Zeitschrift: | 107 |
| DOI: | 10.1016/j.actamat.2016.01.052 |
| Kurzbeschreibung (Abstract): | For magnetocaloric materials the total entropy diagram S(T) in different magnetic fields is of central importance. From such a plot the isothermal entropy change Delta S-T and the adiabatic temperature change Delta T-ad can be well-defined. Aim of this work is to investigate the reversible magnetocaloric effect of Heusler alloys under cycling in terms of the S(T) diagram. For this purpose we selected three different Heusler alloys of Ni-Mn-In with transition temperatures between 200 k and room temperature. The S(T) diagrams of the three materials cover all conceivable shapes and are therefore representative for inverse magnetocaloric Heusler alloys. First we comprehensively analyzed the magnetocaloric properties of this model system using calorimetry, magnetometry and direct measurements of the adiabatic temperature change Delta T-ad and subsequently combined those results into the S(T) diagram. It turns out that under certain measurement conditions significant discrepancies can appear. With the help of in-situ optical microscopy, this effect could be attributed to kinetic relaxation effects in the pure martensite phase before the actual Delta T-ad experiment. Furthermore we found that the S(T) diagram obtained under continuous heating and cooling fails to describe the reversible magnetocaloric properties of minor loops under cycling. Utilizing cyclic measurements of the adiabatic temperature change together with calorimetric data it is however possible to determine the reversible magnetic field induced entropy change Delta S-T in fast operation comparable to real device conditions which can be applied to every magnetocaloric material with a first-order transition. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. |
| Freie Schlagworte: | Magnetocaloric effect, Heusler alloys, Calorimetry, Martensitic transition |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Funktionale Materialien 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften |
| Hinterlegungsdatum: | 11 Mai 2016 12:42 |
| Letzte Änderung: | 11 Mai 2016 12:42 |
| PPN: | |
| Sponsoren: | This work was supported by DFG (Grant No. SPP 1599), European Community 7th Framework Program (Grant No. 310748 DRREAM), Spanish MINECO (Project MAT2013-44063-R) and DGA (Consolidated Group E100). |
| Export: | |
| Suche nach Titel in: | TUfind oder in Google |
 |
Frage zum Eintrag |
Optionen (nur für Redakteure)
 |
Redaktionelle Details anzeigen |
Drucken
Impressum