scholarly journals Energetics and phase diagrams of Fe-Cr and Co-Cr systems from first principles

2002 ◽  
Vol 38 (3-4) ◽  
pp. 205-211 ◽  
Author(s):  
J. Vrestzál ◽  
J. Houserová ◽  
M. Sob
Keyword(s):  
Phase Diagrams ◽  
First Principles ◽  
Thermodynamic Description ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
New Model ◽  
Plane Wave Method ◽  
Physical Information ◽  
Total Energies ◽  
End Members

The first principles computations of the total energies of complex phases have been addressed recently. The structural energy differences, calculated by FLAPW (Full potential augmented plane wave) method, enable us to utilize a more complete physical information about total energy of intermetallic phases and to propose a new model for their thermodynamic description. Our approach is based on the two-sublattice model, similarly as for solid solution phases, but the structural energy differences for end-members in the metastable or unstable structures are obtained by means of first-principles electronic structure calculations. Phase diagrams of Fe-Cr and Co-Cr systems containing the intermetallic sigma-phase (5 inequivalent lattice sites, 30 atoms in repeat cell) are described here as an example of application of our new model.

Thermodynamic Analysis of Steels by Incorporating First-Principles Calculations into the CALPHAD Approach

2007 ◽  
Vol 539-543 ◽  
pp. 2413-2418 ◽  
Author(s):  
Hiroshi Ohtani ◽  
N. Hanaya ◽  
Mitsuhiro Hasebe
Keyword(s):  
Phase Diagrams ◽  
Thermodynamic Analysis ◽  
First Principles ◽  
Experimental Information ◽  
Full Potential ◽  
Calphad Approach ◽  
First Principles Calculations ◽  
Plane Wave Method ◽  
Ternary Phase Diagrams ◽  
High Degree

A thermodynamic analysis of the Fe−M−P (M = Nb, Ti) ternary system has been performed by combining first-principles calculations with the CALPHAD approach. Because of the lack of experimental information available, thermodynamic properties of orthorhombic anti-PbCl2-type FeMP were evaluated using the Full Potential Linearized Augmented Plane Wave method, and the estimated values were introduced into a CALPHAD-type thermodynamic analysis. Applying this procedure, the phase diagrams of the Fe−M−P ternary phase diagrams whose contents are uncertain so far were calculated with a high degree of probability. Phase diagrams for high-purity ferritic stainless steels obtained following the same procedure are also presented.

First-Principles Calculations and the Thermodynamics of Cementite

2010 ◽  
Vol 638-642 ◽  
pp. 3319-3324 ◽  
Author(s):  
Jae Hoon Jang ◽  
In Gee Kim ◽  
H.K.D.H. Bhadeshia
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Lattice Constants ◽  
Unit Cells ◽  
Linearized Augmented Plane Wave

Thermodynamic data for the substitution of silicon and manganese in cementite have been estimated using first-principles methods in order to aid the design of steels where it is necessary to control the precipitation of this phase. The need for the calculations arises from the fact that for silicon the data cannot be measured experimentally; manganese is included in the analysis to allow a comparison with its known behaviour. The calculations for Fe3C, (Fe11Si4c)C4, (Fe11Si8d)C4, (Fe11Mn4c)C4 and (Fe11Mn8d)C4 are based on the total energy all-electron full-potential linearized augmented plane-wave method within the generalized gradient approximation to density functional theory. The output includes the ground state lattice constants, atomic positions and bulk moduli. It is found that (Fe11Si4c)C4 and (Fe11Si8d)C4 have about 52 and 37 kJ greater formation energy when compared with a mole of unit cells of pure cementite, whereas the corresponding energy for (Fe11Mn4c)C4 and (Fe11Mn8d)C4 is less by about 5 kJ mol1. These results for manganese match closely with published trends and data; a similar comparison is not possible for silicon but we correctly predict that the solubility in cementite should be minimal.

First-Principles Studies of the Magnetic Properties of hcp Cr in Cr/Cu(111) and Cr/Ru(0001) Superlattices

2002 ◽  
Vol 721 ◽  
Author(s):  
G. Y. Guo
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Recent Observation ◽  
Theoretical Calculations ◽  
Ferromagnetic State ◽  
Full Potential ◽  
Generalized Gradient ◽  
Plane Wave Method ◽  
Wide Range ◽  
Linearized Augmented Plane Wave

AbstractLatest first-principles density functional theoretical calculations using the generalized gradient approximation and highly accurate all-eleectron full-potential linearized augmented plane wave method, show that bulk hcp Cr would be a paramagnet and that no ferromagnetic state could be stabilized over a wide range of volume [1]. To understand the recent observation of the weakly ferromagnetic state of Cr in hcp Cr/Ru (0001) superlattices [2], the same theoretical calculations have been carried out for the hcp Cr3/Ru7 (0001) and hcp Cr3/fcc Cu6 (111) superlattices. The Cr/Ru superlattice is found to be ferromagnetic with a small magnetic moment of ∼0.31μB/Cr while in contrast, Cr/Cu superlattice is found to be nonmagnetic.

FIRST-PRINCIPLE THEORETICAL STUDY ON THE CALCIUM FERRITE-TYPE LiMn2O4

2010 ◽  
Vol 03 (02) ◽  
pp. 93-96 ◽  
Author(s):  
MEILING LI ◽  
YUE ZHANG ◽  
LIN LI
Keyword(s):  
Magnetic Moments ◽  
Mixed Valence ◽  
Calcium Ferrite ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Augmented Plane Wave Method ◽  
Structural And Electronic Properties ◽  
Mixed Valence Compound ◽  
Linearized Augmented Plane Wave

The structural and electronic properties of the calcium ferrite-type LiMn 2 O 4 were studied using the full-potential linearized augmented plane wave method. The results showed that LiMn 2 O 4 was an antiferromagnetic semiconductor from GGA+U calculations, similar to the experimental report of Li 0.92 Mn 2 O 4. The spin magnetic moments and density of states of Mn atoms showed that LiMn 2 O 4 was a mixed-valence compound with Mn 3+ and Mn 4+ cations randomly distributed amongst the octahedral sites.

Ferromagnetic Material of the Nearly Half-Metallic Alloy Co2TiGa

2013 ◽  
Vol 690-693 ◽  
pp. 590-593 ◽  
Author(s):  
Hong Pei Han
Keyword(s):  
Spin Polarization ◽  
Heusler Alloy ◽  
Ferromagnetic Material ◽  
Full Potential ◽  
Half Metallic ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Linearized Augmented Plane Wave ◽  
Full Heusler ◽  
Metallic Ferromagnetism

The structure, electronic and magnetic properties of full-Heusler alloy Co2TiGa are investigated by means of the full potential linearized augmented plane-wave method. Our results show that the ground state of Co2TiGa is of the nearly half-metallic ferromagnetism with a magnetic moment of 1.00218μBper unit cell, which are contributed by the atoms Co and Ti. Meanwhile, the spin polarization around the Fermi level is up to 93.2%, almost 100%, which indicates that full-Heusler alloy Co2TiGa with the well magnetism and spin polarization would be possibly applied to the field of the material engineering and information technology.

Research on Topological Insulating Materials Induced by Uniaxial Strains with Properties of Insulating Materials

2013 ◽  
Vol 675 ◽  
pp. 180-183
Author(s):  
Hong Pei Han ◽  
Xin Ping Dong
Keyword(s):  
Electronic Band Structure ◽  
Full Potential ◽  
Electronic Band ◽  
Insulating Materials ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Low Energy Consumption ◽  
Temperature Application ◽  
Insulating Phase ◽  
Linearized Augmented Plane Wave

A series of calculations are carried out to investigate systematically the electronic band structure of bulk HgTe under uniaxial strains with the relaxed-volume by means of the full potential linearized augmented plane-wave method. Our results show that there is a topological insulating phase induced by proper uniaxial strains, which is consistent with previous theoretical and experimental results. Interestingly, the strain-induced band gap is large up to 0.21 and 0.17 eV in expansion and compression along c-direction, respectively. It is indicated that the bulk HgTe under proper uniaxial strains would be possibly made the room temperature application for material engineering with low energy consumption.

Sign in / Sign up

Export Citation Format

Share Document