Infrared and Raman studies of amorphous MoS 3 and poorly crystalline MoS 2

Abstract

Amorphous MoS 3 and poorly crystalline MoS 2 have been studied using infrared and Raman spectroscopies. While poorly crystalline MoS 2 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 MoS 3. In contrast to poorly crystalline MoS 2 where sharp Raman peaks were measured at 384 and 408 cm −1, the Raman spectrum of amorphous MoS 3 showed broad peaks at 215, 317, 431, and 528 cm −1. The band profiles of both the ir and Raman spectra of the MoS 3 sample indicate the amorphous nature of the material. This is consistent with results obtained by other techniques. The comparison of the Raman spectrum of MoS 3 and that of amorphous MoS 2 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 MoS 3 is evidence for polysulfide bonds indicated by the XPS spectrum of the material. These results support a chain-like structural model for amorphous MoS 3 similar to that for crystalline MS 3 (M = Ti, Zr, Hf, Nb, Ta, and U). The thermal stability of MoS 3 and the effect of laser power on the Raman spectrum of MoS 3 were also studied.