1 research outputs found
High-Pressure Study of Perovskites and Postperovskites in the (Mg,Fe)GeO<sub>3</sub> System
The effect of incorporation
of Fe<sup>2+</sup> on the perovskite (<i>Pbnm</i>) and postperovskite
(<i>Cmcm</i>) structures was investigated in the (Mg,Fe)ÂGeO<sub>3</sub> system 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 (<i>K</i><sub>0</sub>) and a modest increase in zero-pressure volume (<i>V</i><sub>0</sub>). 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