The structural and magnetic properties of Fe17Dy2Hx compounds, where x was equal to 0, 1, 2, 3 or 3.8, were investigated by means of powder X-ray diffraction, thermomagnetic and alternating-current magnetic susceptibility measurements and 57Fe Mössbauer spectroscopy. The Fe17Dy2Hx compounds crystallized in an hexagonal Ni17Th2-like structure which exhibited both Fe-rich stoichiometry and disorder of the Dy and Fe-Fe dumb-bell sites. The increases in the lattice parameter, magnetic ordering temperature and saturation magnetization, and the dependence of the Mössbauer hyperfine parameters upon H content, indicated a 2-step filling of the interstitial sites with H. The latter first filled the octahedral 6h-sites when x was less than 3, and then partially filled the tetrahedral 12i-sites for x = 3 or 3.8. Neither the Mössbauer spectra nor the alternating-current magnetic susceptibility measurements revealed spin reorientation in any of the compounds. The extent of excess Fe and disorder which was observed in all of the compounds was confirmed by the Mössbauer spectra, and the hyperfine parameters of the Fe 4e-sites were reported here for the first time. The Mössbauer spectra indicated that the interstitial H atoms which partially occupied the tetrahedral 12i-sites jumped between these sites at the Mössbauer timescale.

A Structural, Magnetic and Mössbauer Spectral Study of Dy2Fe17 and its Hydrides. O.Isnard, D.Hautot, G.J.Long, F.Grandjean: Journal of Applied Physics, 2000, 88[5], 2750-9