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.
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