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Elastic and inelastic neutron scattering studies of the Kondo lattice CeCu2Ge2 were performed. AtTN=4.1 K an incommensurate magnetic order develops with an ordering wave vectorq0=(0.28, 0.28, 0.54) and an ordered moment µs=0.74 µB. The crystalline electric field splits the 4f1-J-multiplet of the Ce ion into a ground state doublet and a quartet at 191 K. The wave function of the ground state yields an ordered moment of 1.54µB. Thus, due to the onset of the formation of a Kondo singlet the magnetic moment is considerably reduced. The magnetic relaxation rate Λ was investigated via quasielastic neutron scattering. The temperature dependence of Λ(T) is characteristic of heavy-fermion systems with a high temperature square root dependence and a limiting low temperature value, yielding a Kondo temperatureTK≈10K. The quasielastic component of the scattered neutron intensities persists down to the lowest temperatures, well belowTN. This quasielastic line is regarded as a characteristic feature of heavy-fermion systems and corresponds to the enhanced value of the linear term of the specific heat.

An inelastic neutron scattering study is performed on the new magnetically ordered heavy-fermion systems CeCu2Ge2 and CeAg2Ge2. The temperature dependence of the quasielastic line can be interpreted in terms of a Kondo type of behavior. In addition crystalline electric field transition energies are reported.

The crystal field splittings of the 4f-states in Er(Tl 1- c Pb c ) 3 and Pr(Tl 1- c Pb c ) 3 (cubic, Cu 3 Au-structure) have been investigated by inelastic neutron scattering. The crystal fields are cubic for all mixing ratios c . The crystal field parameters vary linearly with c . The results demonstrate the failure of the point charge model and emphasize the role played by the ligands.

The magnetic relaxation rates Γ as determined via inelastic neutron scattering experiments are reported for the ternary compounds CeM 2 X 2 (M  Ni, Cu, Ag, Au, Ru; X  Si, Ge). Strongly enhanced values of Γ and deviations from a Korringa-type of behaviour were found. A close correlation between the unit cell volume and the 4f-local spin / conduction electron hybridization is demonstrated.

Specific heat, resistivity and inelastic neutron scattering experiments are reported, which demonstrate that CeNi 2 Ge 2 exhibits a heavy-fermion groundstate which is neither magnetic nor superconducting. The specific heat coefficient γ( T ) reaches 350 mJ/K 2 mol and exhibits a peak at 0.4 K showing that coherence effects become important at low temperatures. The magnetic relaxation rates as measured via the line width in inelastic neutron scattering experiments are strongly enhanced and deviate from a Korringa law behaviour. The Kondo temperature T K ≈ 30 K was determined from the magnetic relaxation rates and from the specific heat data.