  The T-dependence of magnetic moments in SrB_6 is studied through
spin-polarized band calculations for a supercell of Sr_{27}B_{156} containing a
B_6 vacancy. The magnetic moment decays rather quickly with T despite the fact
that only electronic Fermi-Dirac effects are included. This result and the
T-dependence of moments near a La impurity can hardly explain the reports of a
very high Curie temperature in hexaborides, but suggest that the magnetism is
caused by some other type of impurity.
