A study of the real structure of intermetallic compounds R_2Fe_(17) (R = Ce, Lu) using neutron powder diffraction, NMR and NGR methods

摘要

The real structure of the Lu_2Fe_(17) compound was shown to be a disordered variant of the Th_2Ni_(17)-type structure for which the exchange of places between Y in 2b-sites and 'dumbbells' of Fe (4f sites) is specific as well as a partial occupation of 4e-position by Fe atoms. Besides, some quantity of Y implants in 2c sites, causing a distortion inside the plane and splitting of Fe 12j-position into two. The real crystal structure of the Ce_2Fe_(17) compound is close to an ideal one of the Th_2Zn_(17)-type. The results of neutron diffraction investigation, which allow one to determine fine structure distortions of the lattices "in the mean" are in good agreement with the NMR and NGR data reflecting local (in terms of interatomic spacings) changes.