  We report the evolution of charge density wave states under pressure for two
NbS3 phases triclinic (phase I) and monoclinic (phase II) at room temperature.
Raman and X-ray diffraction (XRD) techniques are applied. The x-ray studies on
the monoclinic phase under pressure show a compression of the lattice at
different rates below and above 7 GPa but without a change in space group
symmetry. The Raman spectra of the two phases evolve similarly with pressure;
all peaks almost disappear in the 6-8 GPa range, indicating a transition from
an insulating to a metallic state, and peaks at new positions appear above 8
GPa. The results suggest suppression of the ambient charge-density waves and
their subsequent recovery with new orderings above 8 GPa.
