Structural, magnetic, and Mossbauer spectral study of Er2Fe17 and its hydrides - art. no. 014406

The structural and magnetic properties of the Er2Fe17Hx compounds, where x is 0, 1, 2, 3, and 3.8, have been investigated by means of powder x-ray dif fraction, thermal and ac magnetic susceptibility measurements, and iron-57 Mossbailer spectroscopy. The Er2Fe17Hx compounds crystallize in the hexagon al P6(3)/mmc space group with the Th2Ni17-like structure, a structure which has both an iron-rich stoichiometry and disorder of the erbium and iron-ir on 4f-4f dumbbell sites. The increase in the lattice parameters, the magnet ic ordering temperature, the saturation magnetization, and the dependence o f the Mossbauer spectral hyperfine parameters upon the hydrogen content rev eal a two-step filling of the interstitial sites, with hydrogen first filli ng the octahedral 6h sites for x<3 and then partially filling the tetrahedr al l2i sites for x = 3 and 3.8. Neither the Mossbauer spectra nor the ac ma gnetic susceptibility measurements reveal any spin reorientation in any of these compounds. In all of the compounds both the excess amount of iron and the expected disorder is confirmed by the Mossbauer spectra and the hyperf ine parameters of the iron 4e site are reported herein. Finally, the Mossba uer spectra indicate that the interstitial hydrogen atoms partially occupyi ng the tetrahedral 12i sites are jumping between these sites on the Mossbau er time scale.