Investigation of phase transition of mercury decomposed from mercury oxide up to 20GPa

The high pressure behavior of mercury decomposed from mercury oxide up to 20.4GPa was investigated using angular-dispersive X-ray diffraction. The results showed that liquid mercury solidified at 2.0GPa and was resolved as hexagonal, R-3m, a=3.3743 ± 0.0007 Å and c=6.8199 ± 0.0013 Å. When compressed up to 5.7GPa, α mercury transformed into orthorhombic phase γ directly, which is not the case of transforming from an α structure to a body-centered tetragonal structure (β). The space group of orthorhombic phase was interpreted successfully as Pmmn, with a=2.7722 ± 0.0010 Å, b=4.0792 ± 0.0028 Å and c=6.8285 ±0.0029 Å at 8.9GPa.