R3: High-pressure science and deep Earth’s material

[R3-13] Density deficit of Earth’s inner core revealed by a multi-megabar rhenium pressure scale

*Eiji Ohtani¹, Daijo Ikuta¹, Hiroshi Fukui^2,3, Tatsuya Sakamaki¹, Daisuke Ishikawa^4,3, Alfred Q Baron^3,4 (1. Tohoku Uni. Sci., 2. Uni Hyogo, Sci., 3. RIKEN, 4. JASRI)

Keywords:primary pressure scale, high pressure, Earth’s core, density deficit, Inelastic X-ray scattering

We report the first primary pressure scale extending to the multi-megabar pressures of Earth’s core by measuring acoustic phonon velocities using inelastic X-ray scattering from a rhenium sample in a diamond anvil cell. Our new pressure scale agrees with previous primary scales at lower pressures and shock compression experiments, but previous scales have overestimated laboratory pressures by 20% at 230GPa. Our new scale suggests the density deficit of the inner core is ~9%, doubling the light-element content of the inner core.