  Magnetic ordering phenomena in CexPr1-xB6 solid solutions have been studied
using both powder and single-crystal neutron diffraction. A variety of magnetic
structures are observed depending on temperature and Ce concentration. Over a
broad composition range (x $\le$ 0.7), Pr-Pr interactions play a dominant role,
giving rise to incommensurate structures with wave vectors of the form
k{IC1}=(1/4-delta, 1/4, 1/2) or k{IC2}=(1/4-delta, 1/4-delta, 1/2). The
crossover to a CeB6-like regime takes place near x = 0.7-0.8. For the latter
composition, the antiferroquadrupolar phase transition observed in transport
measurements precedes the onset, at lower temperature, of a commensurate
magnetic order similar to that existing in CeB6. However, unlike in the pure
compound, an incommensurate magnetic order is formed at even higher temperature
and persists in the antiferroquadrupolar phase down to the lock-in transition.
These results are shown to reflect the interplay between various type of dipole
exchange and higher multipole interactions in this series of compounds.
