155Gd Mossbauer study of GdFe6Ge6

We have studied the magnetic order of the Gd sublattice in GdFe6Ge6 using the 86.5 keV Gd-155 Mossbauer resonance. The Gd sublattice orders ferromagnetically at 30.8 +/- 0.2 K, independently of the Fe sublattice which orders antiferromagnetically at 489 +/- 5 K. The Gd-155 hyperfine magnetic field at 5 K is -25.6 +/- 0.1 T and the principal component of the electric field gradient tensor (V-ZZ) is +(5.8 +/- 2.1) x 10(20) V m(-2), which corresponds to a second-order crystal-field lattice coefficient A(20) of -22 +/- 9 K a(0)(-2).