The hyperfine parameters of iron atoms are studied in iron nanocrystallites
prepared by different methods: ball milling of iron powder, partial crysta
llization of Fe-Zr-B-Cu amorphous ribbons, and vacuum evaporation of Fe-B p
olycrystalline multilayers. Careful analysis of the spectral contribution o
f the possible impurities and chemical mixing at interfaces reveals that no
specific grain boundary contribution can be separated in the Mossbauer spe
ctra when the grain size is in the 2-10 nm range. The results indicate that
excluding chemical effects the hyperfine fields of iron atoms at the bce i
nterfaces are very close to those in the bulk, and Mossbauer spectra of the
iron nanocrystallites studied can be understood without supposing a separa
te grain boundary phase with very distorted structure or highly reduced den
sity.