[SIT22-P10] Thermal equations of state of MgSiO4H2 phase H up to 63 GPa determined by in situ X-ray diffraction measurement in a multianvil apparatus
Keywords:Thermal equations of state, mantle, phase H, multianvil apparatus, water
Here, we have determined the thermal equations of state of phase H by using in situ X-ray diffraction measurements in conjunction with a multi-anvil apparatus through its stability field from 34 to 63 GPa up to 1300 K. We succeeded to expand the experimental conditions up to 63 GPa by state-of-the-art high-pressure technology using sinter diamond anvils and Al2O3 pressure medium, which achieved higher pressures by ~20 % compared to those using the conventional MgO pressure medium in the similar design of the cell assembly used in Nishi et al. 2014. The data analysis based on the Mie-Grüneisen-Debye model using the third-order Burch-Murnaghan equations at the reference pressure of 35 GPa yielded Vref, =49.61±0.01 (Å3), Kref=344.6±4.1 (GPa), Kref’=3.05±0.32, θref=974±146 (K), γref =1.8±0.1, and q =1.79±0.55. The compressibility of phase H observed in this study is in good agreement with that derived by theoretical calculation in the pressure regions where hydrogen bond symmetrisation is predicted to occur.