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Title: The dynamics of spontaneous hydrogen segregation in LaFe{sub 13−x}Si{sub x}H{sub y}

By means of time- and temperature-dependent magnetization measurements, we demonstrate that the timescale of hydrogen diffusion in partially hydrogenated LaFe{sub 13−x}Si{sub x}H{sub y} is of the order of hours, when the material is held at temperatures close to its as-prepared Curie temperature, T{sub C0}. The diffusion constant is estimated to be D ≈ 10{sup −15}–10{sup −16} m{sup 2} s{sup −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{sub 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.
Authors:
;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)
  2. (Ireland)
  3. Leibniz Institute for Solid State and Materials Research Dresden, 01069 Dresden (Germany)
  4. (Germany)
  5. Materials Science, Technical University Darmstadt, 64287 Darmstadt (Germany)
Publication Date:
OSTI Identifier:
22304352
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; CURIE POINT; DIFFUSION; FREE ENERGY; HYDROGEN; HYDROGEN COMPOUNDS; HYDROGENATION; INTERSTITIALS; IRON COMPOUNDS; LANTHANUM COMPOUNDS; MAGNETIZATION; PARAMAGNETISM; SEGREGATION; SILICON COMPOUNDS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; TIME DEPENDENCE