  We present theoretical results for a Kondo-lattice model with spin-1/2
localized moments, including both the intrasite Kondo coupling and an intersite
antiferromagnetic exchange interaction, treated within an extended mean-field
approximation. We describe here the case of a non-integer conduction-band
filling for which an ``exhaustion'' problem arises when the number of
conduction electrons is not large enough to screen all the lattice spins. This
is best seen in the computed magnetic susceptibility. The Kondo temperature so
obtained is different from the single-impurity one, and increases for small
values of the intersite interaction, but the Kondo-effect disappears abruptly
for low band filling and/or strong intersite coupling; a phase diagram is
presented as a function of both parameters. A discussion of experimental
results on cerium Kondo compounds is also given.
