Infrared and Raman studies of amorphous MoS3 and poorly crystalline MoS2

Amorphous MoS3 and poorly crystalline MoS2 have been studied using infrared and Raman spectroscopies. While poorly crystalline MoS2 exhibits sharp infrared bands at 385 and 470 cm−1, broad bands at 287, 335, 373, and 522 cm−1 were observed for the amorphous MoS3. In contrast to poorly crystalline MoS2 where sharp Raman peaks were measured at 384 and 408 cm−1, the Raman spectrum of amorphous MoS3 showed broad peaks at 215, 317, 431, and 528 cm−1. The band profiles of both the ir and Raman spectra of the MoS3 sample indicate the amorphous nature of the material. This is consistent with results obtained by other techniques. The comparison of the Raman spectrum of MoS3 and that of amorphous MoS2 reported in the literature indicates that local bondings in these materials are dissimilar. The presence of broad bands at 522 cm−1 in ir and 528 cm−1 in Raman spectra of MoS3 is evidence for polysulfide bonds indicated by the XPS spectrum of the material. These results support a chain-like structural model for amorphous MoS3 similar to that for crystalline MS3 (M = Ti, Zr, Hf, Nb, Ta, and U). The thermal stability of MoS3 and the effect of laser power on the Raman spectrum of MoS3 were also studied.