From the study of heat capacity and thermal expansion, of CeNiSn, CeNi
1-xSn1-x (x = 0.05, - 0.05) and CeNi2Sn2 between 0.5 and 25 K, we conc
lude that the competition between the local and long-range antiferroma
gnetic Kondo-type interactions plays a basic role in the formation of
the anomalous gapped ground state.