Previously, the transitions to the noncollinear antiferromagnetic stru
ctures accompanied by the structural distortions have been studied by
a variety of X-ray, magnetic and neutron-diffraction methods. For this
aim we have applied the Mossbauer effect by doping the Fe-57 isotope
to UPdSn. Below T-N, except for the magnetic component, the presence o
f the paramagnetic doublet with the intensity diminishing with decreas
ing temperature have also been observed. As a possible reason for the
occurrence of this doublet in Mossbauer spectra even far below T-N, am
ong others, the fluctuation model of two magnetic phases being in ther
mal equilibrium has been postulated. Moreover, we have calculated and
discussed the dipolar hyperfine fields at the Pd sites (occupied also
by the iron isotope) for various types of magnetic structures reported
in the literature. On this basis, the so-called 'body diagonal' model
of the magnetic structures of UPdSn has been found as being more prob
able. We have also shown that the Mossbauer parameters exhibit an anom
alous behaviour at the critical points, connected with both the struct
ural and magnetic transitions which thus coincide in this compound.