First-principles calculation of L10-disorder phase diagram in FePt system within the first and second nearest neighbor pair interaction energies

Chen, Y.; Iwata, Shuichi; Mohri, Tetsuo

doi:10.1016/s0364-5916(02)80010-4

Cited by 26 publications

(18 citation statements)

References 10 publications

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“…In Ref. 34, the Connolly-Williams method with structures of different concentrations was applied to FePt. Consideration was not limited to the ground state structures.…”

Section: Connolly-williams Methodsmentioning

confidence: 99%

Temperature and particle-size dependence of the equilibrium order parameter of FePt alloys

2005

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First, second and third nearest neighbor pair mixing potentials for equiatomic FePt alloys were calculated from first principles by the Connolly-Williams method within the canonical cluster expansion formalism. It was demonstrated that the Connolly-Williams potentials (based on completely ordered states) and the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) potentials (based on completely disordered state) can be brought into very close correspondence to each other simply by increasing the magnitude of the strain-induced interactions added to the KKR-CPA potential. Using the mixing potentials obtained in this manner, the dependency of equilibrium L10 ordering on temperature was studied for bulk and for (approximately) spherical nanoparticles ranging in size from 2.5 to 6nm. The order parameter was calculated using Monte Carlo simulation and the analytical ring approximation. The calculated order-disorder temperature for bulk (1495-1514 K) was in relatively good agreement (4% error) with the experimental value (1572K). For nanoparticles of finite size, the (long range) order parameter changed continuously from unity to zero with increasing temperature. Rather than a discontinuity indicative of a phase transition, we obtained an inflection point in the order as a function of temperature. This inflection point occurred at a temperature below the bulk phase transition temperature and decreased as the particle size decreased. Our calculations predict that 3.5nm diameter particles in configurational equilibrium at 600• C (a typical annealing temperature for promoting L10 ordering) have an L10 order parameter of approximately 0.84 (compared to a maximum possible value equal to unity). According to our investigations, the experimental absence of (relatively) high L10 order in 3.5nm diameter nanoparticles annealed at 600• C or below is primarily a problem of kinetics rather than equilibrium.

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“…In Ref. 34, the Connolly-Williams method with structures of different concentrations was applied to FePt. Consideration was not limited to the ground state structures.…”

Section: Connolly-williams Methodsmentioning

confidence: 99%

Temperature and particle-size dependence of the equilibrium order parameter of FePt alloys

2005

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“…In the present paper, by reviewing authors' works [14][15][16] on Fe-Pd and Fe-Pt systems and by subsidizing the recent calculation on Fe-Ni systems, an overview of the phase stability and phase equilibria on Fe-based alloys is provided. The organization of the present report is as follows.…”

Section: Introductionmentioning

confidence: 99%

First-principles investigation of L10-disorder phase equilibria of Fe–Ni, –Pd, and –Pt binary alloy systems

Mohri

Chen

2004

Journal of Alloys and Compounds

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“…where k B is the Boltzmann constant, N is the number of [16][17][18][19] within this approximation. For an ordered phase, one needs to distinguish sublattices and the exponents of the entropy formula are modified depending upon the phase of interest.…”

Section: Cluster Variation Methods and Path Probability Methodsmentioning

confidence: 99%

Glass Transition within Cluster Variation and Path Probability Methods

Mohri

2005

Mater. Trans.

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Thermodynamic framework of Crystal-Glass transition is described within the Cluster Variation Method (CVM). Free energy is calculated as a function of order parameter at various temperatures and T 0 diagram is obtained. It is demonstrated that the glass transition temperature can be interpreted as the spinodal ordering temperature in the order-disorder transition. The advantage of the present description is that the kinetic behavior can be investigated within the same framework by employing Path Probability Method (PPM). Therefore, the combination of the CVM and PPM provides a unique theoretical tool to study Crystal-Glass transition in a consistent manner covering thermodynamics and kinetics.

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First-principles calculation of L10-disorder phase diagram in FePt system within the first and second nearest neighbor pair interaction energies

Cited by 26 publications

References 10 publications

Temperature and particle-size dependence of the equilibrium order parameter of FePt alloys

Temperature and particle-size dependence of the equilibrium order parameter of FePt alloys

First-principles investigation of L10-disorder phase equilibria of Fe–Ni, –Pd, and –Pt binary alloy systems

Glass Transition within Cluster Variation and Path Probability Methods

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