Lawrence Berkeley National Laboratory
High-Pressure Study of Perovskites and Postperovskites in the (Mg,Fe)GeO3System
- Author(s): Stan, CV
- Dutta, R
- Cava, RJ
- Prakapenka, VB
- Duffy, TS
- et al.
Published Web Locationhttps://doi.org/10.1021/acs.inorgchem.7b00774
© 2017 American Chemical Society. The effect of incorporation of Fe2+on the perovskite (Pbnm) and postperovskite (Cmcm) structures was investigated in the (Mg,Fe)GeO3system at high pressures and temperatures using laser-heated diamond anvil cell and synchrotron X-ray diffraction. Samples with compositions of Mg# ≥ 48 were shown to transform to the perovskite (∼30 GPa and ∼1500 K) and postperovskite (>55 GPa, ∼1600-1800 K) structures. Compositions with Mg# ≥ 78 formed single-phase perovskite and postperovskite, whereas those with Mg# < 78 showed evidence for partial decomposition. The incorporation of Fe into the perovskite structure causes a decrease in octahedral distortion as well as a modest decrease in bulk modulus (K0) and a modest increase in zero-pressure volume (V0). It also leads to a decrease in the perovskite-to-postperovskite phase transition pressure by ∼9.5 GPa over compositions from Mg#78 to Mg#100.