Magnetic relaxation of hydrogen in RE2Fe17 compounds (RE = Dy, Gd, Y, Nd or Sm)

• Published in: Philosophical magazine. B, Physics of condensed matter. Structural, electronic, optical, and magnetic properties. Physics of condensed matter. Structural, electronic, optical, and magnetic properties., 1999-04, Vol.79 (4), p.585-592
• Main Authors: Mommer, N., Reule, H., Hirscher, M., Kronmüller, H.
• Format: Article
• Language: English
• ISSN: 1364-2812; 1463-6417
• DOI: 10.1080/13642819908205737

The short-range diffusion of hydrogen in RE 2 Fe 17 (RE = Dy, Gd, Y, Nd or Sin) intermetallic compounds was investigated by magnetic after-effect (MAE) measurements. After charging the powder samples in a high-purity H 2 atmosphere (0.13 MPa; 473 K) for 2 days, the hydrogen concentrations for DY 2 Fe 17 H 4.4 , Gd 2 Fe 17 H 3.8 , Y 2 Fe 17 H 3.0 , Nd 2 Fe 17 H 3.5 and Sm 2 Fe 17 H 5.0 were determined by thermal desorption spectroscopy. Charged samples show several hydrogen-induced MAE relaxation maxima in the temperature range between 80 and 220 K. These relaxation maxima are assigned to jumps of hydrogen atoms between various interstitial sites and discussed with respect to possible diffusion paths. Numerical evaluation yielded activation enthalpies of Q = 0.46, 0.46, 0.49, 0.48 and 0.42eV for Gd 2 Fe 17 , Y 2 Fe 17 , Nd 2 Fe 17 , Sm 2 Fe 17 and Dy 2 Fe 17 respectively, for jumps of hydrogen between octahedral sites which are part of the long-range diffusion paths in these compounds as well.