Carbon in the core: sound velocities of the Fe7C3 carbide at extreme conditions

The experiment aims to investigate the density, the elastic and thermodynamic properties of the Fe7C3 carbide at pressures above 300 GPa and temperatures of thousands of degrees utilizing the Nuclear Inelastic Scattering (NIS) technique and powder X-ray diffraction. NIS is a powerful tool for studying lattice dynamics that provides a full thermodynamic sample characterization. The measured phonon density of states provides the Debye phonon average velocity (VD), which together with density and bulk modulus, determined by complementary X-ray diffraction measurements, are the necessary parameters for calculating the compressional velocity (VP) and shear velocity (VS) of the material. Our measurements will allow refining the carbon required to explain the observed seismic profile of the Earth’s core.