We present the room-temperature lattice parameters, the static magnetic susceptibility, and the magnetic resistivity between 2.4 and 300 K for a series of ten polycrystalline $\mathrm{Ce}\left({\mathrm{Pt}}_{1-x}{\mathrm{Ni}}_x\right)\mathrm{Si}$ samples with $x=0.0\mathrm{} \mathrm{to} 1.0$. An abrupt change in the lattice constant as well as in $T_{max}\left({\chi }_m\right)$ and $T_{max}\left({\rho }_m\right)$ occurs around $x=0.5\mathrm{}$. This is evidence for the transition from heavy-fermion behavior to a mixed-valence state. The magnetic-susceptibility and magnetic-resistivity data support the interpretation of resistivity maximum in terms of a spin-scattering mechanism in the mixed-valence regime, while the Kondo scattering mechanism is expected to be valid at high temperature ($T>\mathrm{}{T}_{\mathrm{SF}}$) in the Kondo-lattice regime. From the present study, the heavy-fermion material is believed to be a Kondo-lattice compound with a relatively strong Ruderman-Kittel-Kasuya-Yosida interaction.

• Received 11 March 1987

DOI:https://doi.org/10.1103/PhysRevB.36.5739