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The dynamics of spontaneous hydrogen segregation in LaFe13−xSixHy

Baumfeld, Oliver L. ; Gercsi, Zsolt ; Krautz, Maria ; Gutfleisch, Oliver ; Sandeman, Karl G. (2014)
The dynamics of spontaneous hydrogen segregation in LaFe13−xSixHy.
In: Journal of Applied Physics, 115 (20)
doi: 10.1063/1.4879099
Article, Bibliographie

Abstract

By means of time-and temperature-dependent magnetization measurements, we demonstrate that the timescale of hydrogen diffusion in partially hydrogenated LaFe13-xSixHy is of the order of hours, when the material is held at temperatures close to its as-prepared Curie temperature, T-C0. The diffusion constant is estimated to be D approximate to 10(-15)-10(-16) m(2) s(-1) at room temperature. We examine the evolution of a magnetically phase-separated state upon annealing for 3 days at a range of temperatures around T-C0 and show that the thermodynamic driving force behind hydrogen diffusion and phase segregation may be attributed to the lower free energy of hydrogen interstitials in the ferromagnetic state relative to the paramagnetic state.

Item Type: Article
Erschienen: 2014
Creators: Baumfeld, Oliver L. ; Gercsi, Zsolt ; Krautz, Maria ; Gutfleisch, Oliver ; Sandeman, Karl G.
Type of entry: Bibliographie
Title: The dynamics of spontaneous hydrogen segregation in LaFe13−xSixHy
Language: English
Date: 28 May 2014
Publisher: AIP Publishing LLC
Journal or Publication Title: Journal of Applied Physics
Volume of the journal: 115
Issue Number: 20
DOI: 10.1063/1.4879099
Abstract:

By means of time-and temperature-dependent magnetization measurements, we demonstrate that the timescale of hydrogen diffusion in partially hydrogenated LaFe13-xSixHy is of the order of hours, when the material is held at temperatures close to its as-prepared Curie temperature, T-C0. The diffusion constant is estimated to be D approximate to 10(-15)-10(-16) m(2) s(-1) at room temperature. We examine the evolution of a magnetically phase-separated state upon annealing for 3 days at a range of temperatures around T-C0 and show that the thermodynamic driving force behind hydrogen diffusion and phase segregation may be attributed to the lower free energy of hydrogen interstitials in the ferromagnetic state relative to the paramagnetic state.

Uncontrolled Keywords: MAGNETIC ENTROPY CHANGE, ELECTRON METAMAGNETIC TRANSITION, COMPOUND, MAGNETOSTRICTION, LA(FE, MN
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 17 Nov 2014 09:17
Last Modified: 17 Nov 2014 09:17
PPN:
Funders: The research leading to these results has received funding from the European Community's 7th Framework Programme under Grant Agreement No. 310748 “DRREAM.” , Financial support was acknowledged from The Royal Society (K.G.S.), EPSRC Grant No. EP/G060940/1 (K.G.S. and Z.G.), and an EPSRC DTG studentship is acknowledged by O.L.B.
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