A re-investigation on pressure-induced phase transition of Mg2Si

The high-pressure phase transition of Mg2Si was investigated using angel dispersive synchrotron radiation X-ray diffraction with diamond anvil cell. A phase transition of Mg2Si occurs from the anti-fluorite structure to a monoclinic structure instead of the anti-cotunnite structure at about 11.1 GPa, which is reversible. Isothermal pressure-volume relationship of anti-fluorite Mg2Si is well described by the third-order Birch–Murnaghan equation of state with V0=64.0(2) Å3 and B0=58(2) GPa.

► Two rounds of angle dispersive XRD experiments, one with laser-heating.
► New monoclinic high-pressure phase of Mg2Si, instead of anti-cotunnite phase.
► EoS parameters of anti-fluorite phase was fitted.