Synthesis and compression study of orthorhombic Fe7(C, Si)3: a possible constituent of the Earth's core. Issue 3 (3rd July 2021)

• Record Type: Journal Article
• Authors: Saha, Pinku; Glazyrin, Konstantin; Mukherjee, Goutam Dev
• Is Part Of: High pressure research. Volume 41:Issue 3(2021)
• Page Start: 290
• Page End: 305
• Publication Date: 2021-07-03
• Subjects: Laser-heated diamond anvil cell -- orthorhombic Si-doped Fe7C3 -- elastic anomalies -- Earth's inner core density -- crystal structure; High pressure (Science) -- Periodicals; High pressure (Technology) -- Periodicals; 536.41
• DOI: 10.1080/08957959.2021.1970154
• Languages: English
• ISSNs: 0895-7959

Abstract

ABSTRACT : The orthorhombic phase of Si-doped Fe carbide is synthesized at high-pressures and temperatures using laser-heated diamond anvil cell (LHDAC), followed by its characterization using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Raman spectroscopy. Room-temperature high-pressure XRD measurements are carried out up to about 104 GPa for the determination of the equation of state parameters. No evidence of structural transition is observed. Pressure evolution of isothermal bulk modulus shows elastic stiffening around 28 GPa followed by softening around 78 GPa, which are possibly related to magnetic transitions driven by pressure-induced anisotropic strain in the unit cell. Extrapolation of the density profile of our study to the inner core conditions agrees very well with PREM data with an uncertainty of about 3–4%. Our estimated bulk modulus value at core pressures seems to be 8-9% less than that of PREM data and is best matched in comparison to other reported values.