  We study the formation of local magnetic moments and magnetic hyperfine
fields at an \textit{s-p} impurity diluted in intermetallic Laves phases
compounds $R$Ni$_{2}$ ($R$ = Nd, Sm, Gd, Tb, Dy) at finite temperatures. We
start with a clean host and later the impurity is introduced. The host has
two-coupled ($R$ and Ni) sublattice Hubbard Hamiltonians but the Ni sublattice
can be disregarded because its $\textit{d}$ band, being full, is magnetically
ineffective. Also, the effect of the $\textit{4f}$ electrons of $R$ is
represented by a polarization of the \textit{d} band that would be produced by
the $\textit{4f}$ magnetic field.This leaves us with a lattice of
\textit{effective} rare earth \textit{R}-ions with only \textit{d} electrons.
For the \textit{dd} electronic interaction we use the Hubbard-Stratonovich
identity in a functional integral approach in the static saddle point
approximation.
