First-principles calculations of properties of orthorhombic iron carbide Fe7C3 at the Earths core conditions
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Hidden carbon in Earth's inner core revealed by shear softening in dense Fe7C3.
Earth's inner core is known to consist of crystalline iron alloyed with a small amount of nickel and lighter elements, but the shear wave (S wave) travels through the inner core at about half the speed expected for most iron-rich alloys under relevant pressures. The anomalously low S-wave velocity (vS) has been attributed to the presence of liquid, hence questioning the solidity of the inner co...
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First principles electronic structure calculations based on density functional theory have been used to study the thermodynamic, structural and transport properties of solid solutions and liquid alloys of iron and oxygen at Earth’s core conditions. Aims of the work are to determine the oxygen concentration needed to account for the inferred density in the outer core, to probe the stability of t...
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We summarize the main ideas used to determine the thermodynamic properties of pure systems and binary alloys from first principles calculations. These are based on the ab initio calculations of free energies. As an application we present the study of iron and iron alloys under Earth’s core conditions. In particular, we report the whole melting curve of iron under these conditions, and we put co...
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Introduction: The Earth’s outer core is known to be ~10% less dense than pure metallic Fe-Ni liquid [1, 2] and thus is thought to contain ~10% light elements [e.g., 1] with proposed candidates including sulfur (S), carbon (C), oxygen (O), hydrogen (H), and silicon (Si). The presence of minor, lighter alloying elements is also argued for metallic cores of other planetary bodies including inner t...
متن کاملLaser pyrolysis fabrication of ferromagnetic gamma'-Fe4N and FeC nanoparticles.
Using the laser pyrolysis method, single phase gamma'-Fe4N nanoparticles were prepared by a two step method involving preparation of nanoscale iron oxide and a subsequent gas-solid nitridation reaction. Single phase Fe3C and Fe7C3 could be prepared by laser pyrolysis from Fe(CO)5 and 3C2H4 directly. Characterization techniques such as XRD, TEM and vibrating sample magnetometer were used to meas...
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تاریخ انتشار 2015