Thermal equation of state of (Mg0.9Fe0.1)2SiO4 olivine

In situ synchrotron X-ray diffraction measurements have been carried out on San Carlos olivine (Mg0.9Fe0.1)2SiO4 up to 8 GPa and 1073 K. Data analysis using the high-temperature Birch–Murnaghan (HTBM) equation of state (EoS) yields the temperature derivative of the bulk modulus (∂KT/∂T)P = −0.019 ± 0.002 GPa K−1. The thermal pressure (TH) approach gives αKT = 4.08 ± 0.10 × 10−3 GPa K−1, from which (∂KT/∂T)P = −0.019 ± 0.001 GPa K−1 is derived. Fitting the present data to the Mie–Grüneisen–Debye (MGD) formalism, the Grüneisen parameter at ambient conditions γ0 is constrained to be 1.14 ± 0.02 with fixed volume dependence q = 1. Combining the present data with previous results on iron-bearing olivine and fitting to MGD EoS, we obtain γ0 = 1.11 ± 0.01 and q = 0.54 ± 0.36. In this study the thermoelastic parameters obtained from various approaches are in good agreement with one another and previous results.