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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao https://doi.org/10.1...arrow_drop_down
image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
https://doi.org/10.1103/physre...
Article . 1987 . Peer-reviewed
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Thermodynamic properties of tungsten

Authors: , Grimvall; , Thiessen; , Guillermet;

Thermodynamic properties of tungsten

Abstract

Tungsten has several unusual thermodynamic properties, e.g., very high values of the melting point, the entropy of fusion, the expansion on melting and the lattice anharmonicity. These features are given a semiquantitative explanation, based on the electron density of states N(E). Our treatment includes a numerical calculation of the electronic heat capacity from N(E) and a calculation of the entropy Debye temperature ${\mathrm{FTHETA}}^{S}$(T) from the vibrational part of the experimental heat capacity. ${\mathrm{FTHETA}}^{S}$(T) decreases by 36% from 300 K to the melting temperature 3695 K, the largest drop in ${\mathrm{FTHETA}}^{S}$ for elemental metals. Recent quantum-mechanical ab initio calculations of the difference, ${H}^{\ensuremath{\beta}/\ensuremath{\alpha}}$, in Gibbs energy at T=0 K between the metastable fcc tungsten and the stable bcc phase yield ${H}^{\ensuremath{\beta}/\ensuremath{\alpha}}$=50\ifmmode\pm\else\textpm\fi{}5 kJ/mol, which is much larger than the ``experimental'' values ${H}^{\ensuremath{\beta}/\ensuremath{\alpha}}$=10 and 19 kJ/mol derived from previous semiempirical analyses [the so-called calculation of phase diagrams (``CALPHAD'') method] of binary phase diagrams containing tungsten. We have reanalyzed CALPHAD data, using the results of the first part of this paper. Because of the shapes of N(E) of \ensuremath{\alpha}-W and \ensuremath{\beta}-W, some usually acceptable CALPHAD procedures give misleading results. We give several estimates of ${H}^{\ensuremath{\beta}/\ensuremath{\alpha}}$, using different assumptions about the hypothetical melting temperature ${T}_{f}^{\ensuremath{\beta}}$ of fcc W. The more realistic of our estimates gives ${H}^{\ensuremath{\beta}/\ensuremath{\alpha}}$=30 kJ/mol or larger, thus reducing considerably the previous discrepancy between CALPHAD and ab initio results. The physical picture emerging from this work should be of importance in refinements of the CALPHAD method.

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
34
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Top 10%
Top 10%
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