Neutron scattering, thermal expansion, and magnetostriction measurements have been carried out on the cubic compounds ${\mathrm{CeSbNi}}_x$ $(x=0\mathrm{}–0.4).$ Inelastic neutron scattering studies show a well-defined crystal field (CF) excitation at 4.06 (±0.04) meV and 5.02(±0.05) meV in $x=0.08\mathrm{}$ and 0.15, respectively. The crystal field splitting increases with x compared with the parent compound CeSb (3.19 meV) in spite of the lattice parameter increasing with Ni incorporation. The implication is that the increase in the CF splitting in $x=0.08\mathrm{}$ and 0.15 is due to a collapse of the p-f mixing between the Sb $5p$ holes and the localized Ce $4f$ electrons. The analysis of inelastic spectra of $x=0.15\mathrm{}$ shows that the ground state is a doublet $\left({\Gamma }_7\right),$ which explains the temperature-dependent behavior of the magnetic susceptibility. Thermal expansion shows a dramatic change in behavior with Ni composition. The thermal expansion coefficient exhibits a first-order transition at 15.4 K in CeSb, which disappears for Ni composition as low as $x=0.035,$ as well as in an applied field of 8 T. A large magnetostriction has been observed in CeSb in the magnetic-ordered state as well as in the paramagnetic state. The absolute values of the magnetostriction are reduced considerably in the Ni-incorporated alloys. The volume magnetostriction of $x=0.15\mathrm{}$ alloy exhibits a scaling behavior in the paramagnetic state from which we have estimated the product of the magnetovolume coupling constant and the isothermal compressibility.

• Received 18 February 2000

DOI:https://doi.org/10.1103/PhysRevB.62.12181