Theoretical prediction of the elastic properties of body-centered cubic Fe-Ni-Mg alloys under extreme conditions

2012 ◽  
Vol 92 (7) ◽  
pp. 888-898 ◽  
Author(s):  
K. Kádas ◽  
R. Ahuja ◽  
B. Johansson ◽  
O. Eriksson ◽  
L. Vitos
Keyword(s):  
Theoretical Prediction ◽  
Elastic Properties ◽  
Mg Alloys ◽  
Extreme Conditions ◽  
Body Centered Cubic

CALCULATED STRUCTURAL AND ELASTIC PROPERTIES OF M2InC(M=Sc, Ti, V, Zr, Nb, Hf, Ta)

2008 ◽  
Vol 22 (22) ◽  
pp. 2063-2076 ◽  
Author(s):  
A. BOUHEMADOU
Keyword(s):  
Experimental Data ◽  
Theoretical Prediction ◽  
Ab Initio Calculations ◽  
Sound Velocity ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Finite Strain ◽  
Applied Pressure ◽  
Shear Moduli ◽  
Young’S Moduli

Using ab initio calculations, we have studied the structural and elastic properties of M 2 InC , with M = Sc , Ti , V , Zr , Nb , Hf and Ta . Geometrical optimization of the unit cell is in agreement with the available experimental data. We have observed a quadratic dependence of the lattice parameters versus the applied pressure. The elastic constants are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young's moduli and Poisson's ratio for ideal polycrystalline M 2 InC aggregates. We estimated the Debye temperature of M 2 InC from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of Sc 2 InC , Ti 2 InC , V 2 InC , Zr 2 InC , Nb 2 InC , Hf 2 InC and Ta 2 InC compounds, and it still awaits experimental confirmation.

Elastic properties of iron-rich hcp Fe–Mg alloys up to Earth's core pressures

2008 ◽  
Vol 271 (1-4) ◽  
pp. 221-225 ◽  
Author(s):  
Krisztina Kádas ◽  
Levente Vitos ◽  
Rajeev Ahuja
Keyword(s):  
Elastic Properties ◽  
Mg Alloys ◽  
Earth’S Core ◽  
Earth's Core

scholarly journals THEORETICAL PREDICTION OF ELASTIC CONSTANTS FOR MgO

2013 ◽  
Vol 22 ◽  
pp. 24-27
Author(s):  
B. K. PANDEY ◽  
ANJANI K. PANDEY ◽  
CHANDRA KUMAR SINGH
Keyword(s):  
High Pressure ◽  
Theoretical Prediction ◽  
Elastic Properties ◽  
Pressure Dependence ◽  
Lower Mantle ◽  
Close Agreement ◽  
Elastic Parameter ◽  
Shearing Stress ◽  
Pressure Condition ◽  
Precise Knowledge

Precise knowledge of the elastic properties of MgO periclase, under high-pressure condition is therefore crucial for constructing the accurate mineralogical model of the Earth's lower mantle. In present work an attempt has been done to calculate the pressure dependence elastic properties such as isothermal bulk modules (KT), Young's modulus of elasticity Y and shearing stress G for geophysical MgO by using three deferent phenomenological EOS viz. the Born-Mayer EOS, Murnaghan EOS and Birch EOS. The result shows that the value of elastic parameter as calculated by using Murnughan EOS and Birch EOS shows close agreement with each other while Born-Mayer EOS shows deviation in calculated values.

scholarly journals Stability of body-centered cubic iron–magnesium alloys in the Earth's inner core

2009 ◽  
Vol 106 (37) ◽  
pp. 15560-15562 ◽  
Author(s):  
Krisztina Kádas ◽  
Levente Vitos ◽  
Börje Johansson ◽  
Rajeev Ahuja
Keyword(s):  
Inner Core ◽  
The Body ◽  
Mg Alloys ◽  
Functional Study ◽  
Body Centered Cubic ◽  
Calculated Density ◽  
The Core ◽  
Earth’S Inner Core ◽  
Core Conditions ◽  
Bcc Phase

The composition and the structure of the Earth's solid inner core are still unknown. Iron is accepted to be the main component of the core. Lately, the body-centered cubic (bcc) phase of iron was suggested to be present in the inner core, although its stability at core conditions is still in discussion. The higher density of pure iron compared with that of the Earth's core indicates the presence of light element(s) in this region, which could be responsible for the stability of the bcc phase. However, so far, none of the proposed composition models were in full agreement with seismic observations. The solubility of magnesium in hexagonal Fe has been found to increase significantly with increasing pressure, suggesting that Mg can also be an important element in the core. Here, we report a first-principles density functional study of bcc Fe–Mg alloys at core pressures and temperatures. We show that at core conditions, 5–10 atomic percent Mg stabilizes the bcc Fe both dynamically and thermodynamically. Our calculated density, elastic moduli, and sound velocities of bcc Fe–Mg alloys are consistent with those obtained from seismology, indicating that the bcc-structured Fe–Mg alloy is a possible model for the Earth's inner core.

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