Spin transition of ferropericlase under shock compression

Planar shock compression experiments are performed at 9-105 GPa on polycrystalline ferropericlase (Mg0.94Fe0.06)O to investigate its Fe2+ spin transition. Forward and reverse impact configurations are used to obtain Hugoniot and shock-state sound velocities. While wave profiles, shock velocity-particle velocity and pressure-density measurements show negligible/weak indications of a phase transition, the shock-state sound speed data clearly manifest a phase transition in the range of 36-62 GPa at the nanosecond time scales. These shock data reveal the phase transition as the spin transition identified in static compression experiments and first-principles calculations. (C) 2018 Author(s).