Transmission spectra of lithium intercalation complexes of some layered transition-metal dichalcogenides

Abstract

The room-temperature spectra of the undistorted, trigonal prismatic coordinetion Group VA transition-metal dichalcogenides and their intercalation complexes formed with lithium have been measured in the energy range 0.5 to 6.0 eV. The spectral changes induced by intercalation can be interpreted broadly in terms of a rigid-band model, charge transfer from the ionized lithium to the lowest unoccupied d-band states of the host material resulting in the complexes tending towards semiconducting behaviour a t saturation. However, there is probably s-band lowering modifying the band structure as in the Group IVA complexes and the fact that the NbSe, complex apparently remains metallic even at eaturation could indicate that this lowered band overlaps the occupied d-conduction-band states in this particulclr complex.