The stability and equation of state of the post-perovskite phase in MgGeO3 were investigated to 2 Mbar by in situ x-ray diffraction experiments using the laser-heated diamond cell as well as by theoretical calculations using density functional theory. The stability of the phase was demonstrated at 92-201 GPa during laser heating. By using the Birch-Murnaghan equation of state, we obtained a zero-pressure volume (V0) of 179.2 ± 0.7 Å3, bulk modulus (K0) of 207 ± 5 GPa with a pressure derivative (K′0) of 4.4 from experiments at room temperatures, and V0 = 178.02 Å3, K0 = 201.9 GPa, K′0 = 4.34 from theoretical calculations at 0 K. The relative axial compressibilities of the silicate and germanate post-perovskite phases are similar although MgSiO3 is more anisotropic than MgGeO3.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)