Pressure-induced phase transition of HgS

The high pressure phase transition of cinnabar (α-HgS) was studied by energy dispersive x-ray diffraction using a synchrotron x-ray source. The cinnabar crystal structure was found to transform to the sodium–chloride structure at about 130 kbar. The lattice parameter of the new phase was determined to be 5.070±0.005 A at 300 kbar. No further phase transition was observed up to 400 kbar.