VIBRATIONAL STUDY OF LITHIUM INSERTION AND BONDINGS IN INTERCALATED LI3HFS3 AND LI1.5NIPS3 SEMICONDUCTING PHASES

Infrared transmission spectra (600-50 cm(-1)) and Raman spectra (800-1 0 cm(-1)) of the layered semiconducting transition metal sulphides HfS 3 and NiPS3 and of their intercalates LixHfS3, NaxHfS3 (0 < x less tha n or equal to 3) and LixNiPS3 (0 < x less than or equal to 1.5) are co mpared, In agreement with previous studies, it is concluded that alkal i metal ions are accommodated in both tetrahedral and octahedral sulph ur environments in the former case and only in octahedral surroundings in the latter, The wavenumbers of the characteristic intercalation mo des are discussed and compared with literature data; simple local symm etry arguments can then explain the very weak Raman intensity of the m odes in LixNiPS3 compounds.