  We report 7Li NMR, magnetic susceptibility, and heat capacity measurements on
the triangular lattice Heisenberg antiferromagnet compound LiCrO2. We find that
in contrast to NaCrO2, magnetic properties of LiCrO2 have a more pronounced
three dimensional character with sharp anomalies in the temperature variation
of the 7Li NMR intensity and the NMR spin-lattice relaxation rate 1/T1. From
heat capacity measurements we find that the total entropy related to the
magnetic transition is in agreement with expectations. However, we find a
significant contribution to the magnetic entropy in the range from the ordering
temperature T_N to nearly 4T_N. This suggests the existence of magnetic
correlations at temperatures well above T_N which might be due to the
frustrated nature of the system. Based on the temperature dependence of 1/T1,
we discuss the possible occurrence of a Kosterlitz-Thouless-Berezinskii
transition taking place at T_KTB = 55 K in LiCrO2. Lithium depletion has no
significant effect on the magnetic properties and the behaviour of Li0.5CrO2 is
nearly unchanged from that of LiCrO2.
