  Neutron powder diffraction measurements have been performed on
Ce_xNd_{1-x}B_6 (x = 0.5, 0.6, 0.7, and 0.8) solid solutions to determine the
type of magnetic order occurring in these compounds as a result of the
interplay between magnetic dipole exchange and antiferroquadrupolar
interactions. In the Ce-rich range, the sequence of two magnetic phases, with
an incommensurate order [k = (1/4 -\delta, 1/4 -\delta, 1/2)] forming below T N
followed by a lock-in--type transition at lower temperature, is quite similar
to that reported earlier for Ce_xPr_{1-x} B_6. For x = 0.5, on the other hand,
the same antiferromagnetic order as in pure NdB6 first occurs at TN, then
coexists with an incommensurate component below the lower transition
temperature. These results are in good agreement with previous resistivity
measurements and support the idea that Ce and Nd magnetic moments in this
system can be relatively decoupled.
