Metallic properties of lithium-intercalated ZrS2

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Abstract
The lithium intercalation complexes of the group IV transition-metal dichalcogenides TX2 with T=Ti,Zr,Hf and X=S, Se have the properties of d-band metals, with the lithium valence electron transferred to the transition-metal d band which is empty in the unintercalated material. The authors report measurements of the low-temperature heat capacity of ZrS2 and LiZrS2; LiZrS2 has a large linear electronic heat capacity gamma T with gamma =8.5 mJ K-2mol-1, and its T3 lattice heat capacity is very similar to that of ZrS2 with derived values for the Debye temperature of 176 and 188 K respectively. The magnetic susceptibility of LiZrS2-1.2*10-5 emu mol-1 at room temperature, shows a temperature-independent paramagnetic term associated with the conduction electrons of 7.8*10-5 emu mol-1. The resistivity and Hall coefficient for LixZrS2 show the expected metallic behaviour with increasing x as the d conduction band is filled, and there are, for high concentrations of lithium, weak anomalies possibly associated with a structural distortion. These properties contrast with the very strong Fermi-surface-driven structural distortions seen in the 'isoelectronic' group V materials IT-TaS2 and IT-TaSe2.