Substitutional effects in RFe3 intermetallics (R=Dy, Sm, Y)

Samples of RFe3 (R=Dy, Sm, Y) were doped with Si, Al and Ti and studied by Mِssbauer spectroscopy and X-ray diffraction. Most Mِssbauer spectra were analyzed with three sextets, corresponding to the 6c, 3b and 18 h inequivalent lattice sites for iron. A quadrupole split doublet was also present in some spectra, which became dominant for the case of Al substitution. The collapse of the hyperfine magnetic structure is a magnetic effect due to substitutions: the X-ray diffraction patterns yielded a particle size of about 100 nm, thus precluding the occurrence of superparamagnetism in these systems.