The Neel temperature T-N in the tetragonal (P4/mbm space group) antife
rromagnetic U-2(Ni1-xPdx)(2)Sn solid solution exhibits a minimum (T-N=
12(1) K) at x approximate to 0.30-0.35; the end values being respectiv
ely equal to T-N=25 K (x=0) and T-N=42 K (x=1). In order to understand
this T-N vs. x dependence, we have investigated the U-2(Ni0.70Pd0.30)
(2)Sn stannide by neutron powder diffraction. This alloy exhibits two
magnetic transitions, at T-N=11.5(5) K and T-N'=8.0(5) K. Between T-N'
and T-N, the magnetic peaks are associated to k=(001/2) propagation v
ector; below T-N', two propagation vectors are present, k=(0 0 1/2) an
d k'=(1/21/21/2), which are associated to different volumes of the sam
ple. We discuss this complex magnetic behaviour, in connection with th
e U2Ni2Sn (k=(0 0 1/2)) and U2Pd2Sn (k''=(0 0 0)) magnetic structures.
(C) 1998 Elsevier Science S.A.