Thermodynamic properties and equation of state of fcc aluminum and bcc iron, derived from a lattice vibrational method

Jacobs, M.H.G.; Schmid–Fetzer, Rainer

doi:10.1007/s00269-010-0371-6

Cited by 66 publications

(19 citation statements)

References 95 publications

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“…There have been a number of efforts to create predictive thermodynamics models by resolving the entropy into contributions from phonons, spins, and electrons 7,9,10 . Phonons make the largest contribution to the entropy at elevated temperatures, therefore the accuracy of the phonon entropy is critical.…”

Section: Introductionmentioning

confidence: 99%

Nonharmonic phonons inα-iron at high temperatures

et al. 2014

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Phonon densities of states (DOS) of bcc α-57 Fe were measured from room temperature through the 1044K Curie transition and the 1185K fcc γ-Fe phase transition using nuclear resonant inelastic x-ray scattering. At higher temperatures all phonons shift to lower energies (soften) with thermal expansion, but the low transverse modes soften especially rapidly above 700K, showing strongly nonharmonic behavior that persists through the magnetic transition. Interatomic force constants for the bcc phase were obtained by iteratively fitting a Born-von Kármán model to the experimental phonon spectra using a genetic algorithm optimization. The second-nearest-neighbor fitted axial force constants weakened significantly at elevated temperatures. An unusually large nonharmonic behavior is reported, which increases the vibrational entropy and accounts for a contribution of 35 meV/atom in the free energy at high temperatures. The nonharmonic contribution to the vibrational entropy follows the thermal trend of the magnetic entropy, and may be coupled to magnetic excitations. A small change in vibrational entropy across the α-γ structural phase transformation is also reported.

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Section: Introductionmentioning

confidence: 99%

Nonharmonic phonons inα-iron at high temperatures

et al. 2014

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“…(13), Stacey and Isaak [22] pointed out that / 2 1/ 6 K     (14) (12) 4 Based on the Keane's EOS, Shanker and Singh [23] (14) and (15) [20].…”

Section: Analysis and Resultsmentioning

confidence: 98%

“…To understand the thermodynamic properties of solids, such as the phenomenon of melting, et al, the study of the volume dependence of Grüneisen parameter  is of central importance from theoretical as well as experimental point of view. Many workers have discussed  of fcc Al in pressure-temperature space [1][2][3][4][5][6]. McQeen et al [7] suggested that the Grüneisen ratio itself be of a form as 0 x   (1) where x = 0 / VV is the compression ratio, the subscript "0" represents the corresponding zero pressure values.…”

Section: Introductionmentioning

confidence: 99%

“…Jacobs et al [4] used a lattice vibrational technique to derive thermophysical and thermochemical properties of fcc Al in pressure-temperature space. They concluded that the Keane's equation of state (EOS) [16] for the static lattice is better suitable to represent thermodynamic data for aluminum from 1 bar to pressures in the multi-megabar region relative to Vinet's universal [17] and the Birch-Murnaghan EOS [18].…”

Section: Introductionmentioning

confidence: 99%

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A comparative study of Burakovsky's and Jacobs's volume dependence Grüneisen parameter for fcc aluminum

Nie¹,

Zong²,

Wang³

2015

Physica B: Condensed Matter

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“…Recent years have seen significant progress in probing thermodynamic properties of iron [9][10][11][12][13][14][15][16] . Neuhaus et al 11,12 performed inelastic neutron scattering measurements of the phonon dispersions of iron at high temperatures near the distinct phase transitions, and they found that the vibrational and electronic entropies contribute almost equally at the α-γ transition, while the vibrational contribution dominates at the γ-δ transition, stemming from the low-energy transverse phonons in the open bcc lattice of the δ phase.…”

Section: Introductionmentioning

confidence: 99%

Ab initiostudy of the anharmonic lattice dynamics of iron at theγ−δphase transition

2015

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We report calculations of phonon dispersions of iron (Fe) at its γ−δ phase transition using a self-consistent ab initio lattice dynamical method in conjunction with an effective magnetic force approach via the antiferromagnetic approximation. Our results show that anharmonic phononphonon interactions play a crucial role in stabilizing the δ-Fe phase in the open bcc lattice. In contrast, the lattice dynamics of the close-packed fcc γ-Fe phase are dominated by magnetic interactions. Simultaneous considerations of the lattice anharmonic and magnetic interactions produced temperature-dependent phonon dispersions for δ-Fe and γ-Fe phases in excellent agreement with recent experimental measurements. The present results highlight the key role of lattice anharmonicity in determining the structural stability of iron at high temperatures, which has significant implications for other high-temperature paramagnetic metals like Ce and Pu.

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Thermodynamic properties and equation of state of fcc aluminum and bcc iron, derived from a lattice vibrational method

Cited by 66 publications

References 95 publications

Nonharmonic phonons inα-iron at high temperatures

Nonharmonic phonons inα-iron at high temperatures

A comparative study of Burakovsky's and Jacobs's volume dependence Grüneisen parameter for fcc aluminum

Ab initiostudy of the anharmonic lattice dynamics of iron at theγ−δphase transition

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