The DyNi5−xAlx compounds crystallize in CaCu5-type structure for an aluminum content x⩽1.5 and in HoNi2.6Ga2.4 type for x⩾2. The saturation moments per formula unit extrapolated at 0 K, in composition range x<2 are ∼9.2 μB in agreement with x-ray photoelectron spectroscopy studies which show negligible crystal field effects. For x⩾2 a mictomagnetic type contribution to magnetic ordering develops which becomes dominant only for the DyNi2Al3 compound. Band structure calculations on DyNi5−xAlx show that the Dy 5d band is polarized parallel to the 4f moment. For DyNi5 the nickel moments at 2c and 3g sites are antiparallel oriented to that of Dy. The nickel contributions to magnetization decrease when increasing aluminum content and are near nil for x⩾2. Above the Curie points the reciprocal susceptibilities follow linear dependencies. The effective nickel moments decrease from 2.11 μB/atom (x=0) to 0.87 μB/atom (x=2.5). The magnetic behavior of nickel is analyzed in models which take into account the electron correlation effects in d bands.

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