20 research outputs found
Thermal conductivity of iron and nickel during melting: Implication to Planetary liquid outer core
We report the measurements of the thermal conductivity () of iron
(Fe) and nickel (Ni) at high pressures and high temperatures. values
are estimated from the temperature measurements across the sample surface in a
laser heated diamond anvil cell (LHDAC) and using the COMSOL software.
Near-isothermal 's are observed to increase with pressure in both the
metals due to the increase of density of the pressed metals. In both metals
's are observed to follow a sharp fall during melting at different
pressure points and are consistence with the other multi-anvil measurements.
Constant values of in these metals during melting at different
pressures reveal the loss of long range order, which creates independent
movement of atomic metals. The melting temperature measured in these metals
from the sudden drop of -values are in a good agreement with the other
melting measurements in LHDAC. The results obtained in this study is expected
to provide an insight to the studies on the planets Mercury and Mars and their
interior
Synthesis and compression study of orthorhombic Fe(C, Si) : a possible constituent of the Earth’s core
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