The evolution of the crystal-field states upon increasing hybridization in

Inelastic neutron scattering (INS) experiments have been performed on polycrystalline for the concentrations x = 0.1, 0.28, 0.5, 0.65 to study the effect of the increasing hybridization between the f electrons and the band states on the crystal-field (CF) states. For both x = 0.1 and x = 0.28, CF level schemes very similar to that of pure have been found. In contrast, no well defined CF excitations could be detected for x = 0.5 and x = 0.65. The absence of properly developed CF states in high- Kondo and/or valence fluctuation compounds is a well known fact. Remarkably, in for x = 0.5 and x = 0.65, the Kondo temperatures as determined by quasielastic neutron scattering are at least one order of magnitude below the typical CF splitting energies observed for x = 0.1 and x = 0.28. The evolution of the CF splitting in and its distinctive behaviour is discussed in comparison with other heavy-fermion compounds.