An investigation of the hydrogen desorption from Nd2Fe17Hx, and Dy2Fe17Hx compounds by differential scanning calorimetry

F. Cuevas (1) , Olivier Isnard (2) , B. Villeroy (1)

1 ICMPE - Institut de Chimie et des Matériaux Paris-Est
2 NEEL - MRS - Matériaux, Rayonnements, Structure

Hydrogen desorption from R2Fe17Hx, (R=Nd and Dy) compounds with x <= 5 has been studied using differential scanning calorimetry (DSC). Overall hydrogen binding energies are very similar in both systems regardless their different crystal structures. The heat of hydrogen desorption is 29.2 +/- 0.8 kJ mol H-1 for both R2Fe17Hx family compounds. Desorption activation energies are also very close: 78 +/- 8 kJ and 79 +/- 4 kJ mol H-1 for Nd and Dy-containing compounds, respectively. The rare earth nature modifies however the local interaction between hydrogen and the intermetallic compound. For Nd, H-atoms occupy two non-equivalent and well-defined energy sites whereas a unique energy site with a broad energy distribution is detected for Dy. This peculiar behavior is discussed in terms of the different structural properties of the light (Nd) and heavy (Dy) rare-earth R2Fe17 compounds.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

F. Cuevas, Olivier Isnard, B. Villeroy. An investigation of the hydrogen desorption from Nd2Fe17Hx, and Dy2Fe17Hx compounds by differential scanning calorimetry. Thermochimica Acta, 2013, 561, pp.14-18. ⟨10.1016/j.tca.2013.03.019⟩. ⟨hal-00989319⟩