LINESHAPES OF ESR SIGNALS AND THE NATURE OF PARAMAGNETIC SPECIES IN AMORPHOUS MOLYBDENUM SULFIDES

Amorphous and poorly crystallized molybdenum sulfides were studied by ESR. Qualitative analysis of the spectra suggests the presence of three paramagnetic species. A simulation of the ESR spectra was attempted on this basis. ESR lines were calculated over the stoichiometry range MoS3 --> MoS2. A good representation of the main part of the experimental lines was obtained. There is no significant variation of the g values of the various components of the spectra during the transformation from MoS3 to MoS2. The first signal is attributed to sulfur centers. The two others are assigned to metal centers. One is due to Mo(v) sites in a chain-like structure, observed in the amorphous phase of MoS3. The other is due to Mo(v) defects in a layered MoS2 microstructure. The variation of the site concentration was calculated for all compounds, from MoS3 to MoS2.