NEUTRON-SCATTERING AND X-RAY-DIFFRACTION STUDY OF THE VALENCE-UNSTABLE SYSTEM CE1-XLAXNISN

Valence-unstable systems such as Ce1-xLaxNiSn have been studied by inelastic neutron scattering and X-ray diffraction in the temperature range 10-300 K. Magnetic response shows no evidence of crystal field effects, but quasi-elastic scattering is present. No considerable changes in the properties investigated due to Ce substitution by La in the small-x range were found. Strong anisotropy and different temperature dependence of the linear thermal expansion coefficients for CeNiSn and LaNiSn have been established. The evidence was obtained that coherent interaction in the electronic system is responsible for the gap formation at low temperatures.