FRUSTRATION OF MAGNETIC-INTERACTIONS IN HEAVY-FERMION COMPOUNDS - CENI2-XSN2 AND OTHER 1 2/2 COMPOUNDS/

The crystallographic structure of CeNi2-xSn2 compound is reinvestigate d. Two phases occur depending on preparation, the first being tetragon al, the other monoclinic with some Ni deficiency. The antiferromagneti c structure below T-N = 21 K is shown to be highly frustrated. The mea sured order ed moment reaches 0.90 mu(B) at 1.5 K, 78% of the value ca lculated for a crystal field ionic model. This reduction is in agreeme nt with that inferred from the analysis of specific heat data. We disc uss the occurrence of magnetic frustration, its incidence on long rang e order and on the anisotropy of the magnetic correlation length in re lated systems.