EPR studies of Gd as a probe of uranium intermetallic compounds and YbCuAl

g-shifts and linewidths in the X band are given for Gd impurities substituted for U in UAl2, UCo2 and URh3, and for Yb in YbCuAl. No resonance was observed for the first of these alloys, an effect ascribed to 5f spin-fluctuation character. For the other U compounds Δg and the temperature dependence of the linewidth were fairly small. For YbCuAl a very large positive g-shift and a strong temperature dependence of linewidth were observed, These results are compared with those for other materials in which spin-fluctuation or intermediate-valence character have been suggested. (author)