CRYSTAL-FIELD IN VALENCE-FLUCTUATING CENI-BASED COMPOUNDS

The effects of the crystal field (CF) on the paramagnetic Pr ion in a number of compounds of the type R(1-x)Pr(x)Ni (R = Ce, La, Y), in whic h a transition of the cerium ions from an intermediate-valence into a Kondo state occurs as La is substituted for Ce, are investigated. The level schemes of the Pr ion in the CF are reconstructed from inelastic neutron scattering spectra and the temperature dependence of the heat capacity in different magnetic fields (B = 0-8 T). The parameters of the low-symmetry CF in the compounds RNi are determined from the exper imental data. It is established that in the Kondo regime the hybridiza tion of the f electrons with conduction electrons only gives a proport ional increase in all the parameters of the CF potential. At the same time, partial delocalization of the f electrons in the intermediate-va lence state results in charge redistribution, which is manifested in d ifferent scales for the changes in the different CF parameters. (C) 19 96 American Institute of Physics.