  Pressure-induced phase transitions of multiferroic BiFeO3 have been
investigated using synchrotron radiation X-ray diffraction with diamond anvil
cell technique at room temperature. Present experimental data clearly show that
rhombohedral (R3c) phase of BiFeO3 first transforms to monoclinic (C2/m) phase
at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with
recent theoretical ab initio calculation. However, we observe another peak at
2{\theta}=7{\deg} in the pressure range of 5-7 GPa that has not been reported
previously. Further analysis reveals that this reflection peak is attributed to
the orthorhombic (Pbam) phase, indicating the coexisting of monoclinic phase
with orthorhombic phase in low pressure range.
