Solid State Ionics, Vol.92, No.1-2, 37-43, 1996
Raman-Scattering Studies of Lithium-Intercalated Nips3
We report on the vibrational properties of lithium-intercalated NiPS3 microcrystalline samples. Raman scattering spectra of LixNiPS3 (0 less than or equal to x less than or equal to 1.16) compounds have been recorded as a function of temperature in the wavenumber range 50-700 cm(-1). The new peak located at 313 cm(-1) is interpreted as a stretching mode due to vibration of lithium atoms located in the van der Waals gap against the nearest neighbouring sulphur atoms. Results are analyzed in terms of stretching vibrations of LiS6 entities. It is concluded that lithium ions are more likely to occupy octahedral sites in the lithium-rich phase. Using a simple model of lattice dynamics, the coupling force constants are determined and compared with those in the pristine material.