Physical properties of first and second stage lithium graphite intercalation compounds

Abstract

The second stage lamellar compound of graphite with lithium (LiC 12) has been investigated by specific heat and magnetic susceptibility experiments at low temperatures. The heat capacity thermal variation in the He 4 temperature range is fitted, as usual, with linear and cubic T-dependent terms. This fit allows us to calculate the density of levels at Fermi energy: N( E F) = 2.2 ± 0.2 eV −1 molecule −1 and the Debye temperature θ D = 142 K for a mole of product. The magnetic measurements between 295 and 5 K, indicate a temperature independent term χ exp = (0.85 ± 0.10)10 −6 emu CGS g −1 . After corrections for the usual core diamagnetism we obtain a mean Pauli component equal to (1.85 ± 0.2)10 −4 emu CGS mole −1 which is about twice as large as expected from the above calculated N( E F). Comparison of these experimental data with those already obtained for the first stage compound has been made. Referring to other physical properties, such as e.p.r., and plasma resonance, it is shown that these materials behave as weakly anisotropic 3D electronic systems.