Electronic structure of liquid tungsten studied by time-resolved photoelectron spectroscopy

Wahrenberg, R.; Stupp, H.; Boyen, Hans‐Gerd; Oelhafen, P.

doi:10.1209/epl/i2000-00219-7

Cited by 14 publications

(9 citation statements)

References 20 publications

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“…We refer to this as non-thermally assisted ultrafast melting due to the significant decrease in the melting temperature arising from changes in the empirical potential at elevated electronic temperatures. We note that Wahrenberg et al have observed the presence of a fcc-like liquid phase on the surface of laser irradiated tungsten from time-resolved photoelectron spectroscopy 66 .…”

Section: T-md Simulations Of Laser Irradiation Of W Thin Filmsmentioning

confidence: 65%

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

et al. 2015

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The rearrangement of a material's electron density during laser irradiation leads to modified non-thermal forces on the atoms that may lead to coherent atomic motions and structural phase transformations on very short timescales. We present ab initio molecular dynamics simulations of a martensitic solid-solid phase transformation in tungsten under conditions of strong electronic excitation. The transformation is ultrafast, taking just over a picosecond, and follows the tetragonal Bain path. To examine whether a solid-solid bccfcc phase transformation could occur during laser irradiation, we use two-temperature molecular dynamics (2T-MD) simulations with a specially developed potential dependent on the electronic temperature. Our simulations show that the occurrence of the solid-solid phase transformation is in competition with ultrafast non-thermally assisted melting with the strength of the electron-phonon coupling determining the lifetime of the new solid phase. In tungsten the melting transition is predicted to occur too rapidly for the fcc phase to be detectable during laser irradiation.

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Section: T-md Simulations Of Laser Irradiation Of W Thin Filmsmentioning

confidence: 65%

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

et al. 2015

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“…show changes in the DOS in the solid and liquid which reflect the changes in atomic ordering from bcc to a close-packed-like ordering [23][24][25].…”

Section: Molybdenummentioning

confidence: 99%

Melting of aluminum, molybdenum, and the light actinides

2004

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A semi-empirical model was used to explain why the measured melting curves of molybdenum, and the other bcc transition metals, have an unusually low slope (dT/dP~0). The total binding energy of Mo is written as the sum of the repulsive energy of the ions and sp-electrons (modeled by an inverse 6 th power potential) and the d-band cohesive energy described by the well known Friedel equation. Using literature values for the Mo band width energy, the number of d-electrons and their volume dependence, we find that a small broadening of the liquid d-band width (~1%) leads to an increase in the stability of the liquid relative to the solid. This is sufficient to depress the melting temperature and lower the melting slope to a value in agreement with the diamondanvil cell measurements. Omission of the d-band physics results in an Al-like melting curve with a much steeper melt slope. The model, when applied to the f-electrons of the light actinides (Th-Am), gives agreement with the observed fall and rise in the melting temperature with increasing atomic number.

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“…It has been established that these calculations can accurately determine the melting curve of nearly free electron metals, such as aluminium (Al) [24], where the interatomic forces remain relatively unchanged upon melting [17]. However, this is not the case of bcc transition metals, where the electronic structure is rearranged upon melting [17,25]. This different behaviour of bcc transition metals is quite significant for melting [17] and may be a possible cause for the large melting temperatures obtained from ab initio calculations, since these calculations does not take into account the free energy changes produced by the alterations of the delectron band of Mo upon melting.…”

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confidence: 99%

Improving the understanding of the melting behaviour of Mo, Ta, and W at extreme pressures

Errandonea

2005

Physica B: Condensed Matter

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We discus existent conflicts between experimentally measured and theoretically calculated melting curves of Mo, Ta, and W. By assuming that vacancy formation plays a fundamental role in the melting process, an explanation for the measured melting curves is provided.Furthermore, we show that the Lindemann law fits well all the measured melting curves of bcc transition metals if the Grüneisen parameter is written as a power series of the interatomic distance. For completeness, we examine possible reasons for current disagreements between shockwave and DAC experiments. To solve them, we propose the existence of an extra high P-T phase for Mo, Ta, and W.In materials science and geophysics, it is essential to understand how elements undergo the transition between solid and liquid phases at high pressures. For example, an accurate picture of materials performance under extreme conditions and detailed models of planetary interiors both depend on this knowledge. In recent years, the generation and measurement of simultaneous high pressures and high temperatures has undergone rapid development with the diamond-anvil cell (DAC) technique [1 -3]. As a consequence of this, the amount of available data on melting behaviour at high pressure is increasing [4,5]. The bcc transition metals (i.e. molybdenum (Mo), tantalum (Ta), and tungsten (W)) are especially interesting in this regard because they have very high melting points at ambient pressure and, in addition, at room temperature (RT) they remain in a stable body-centered cubic (bcc) structure up to extremely high pressures [6,7]. Mo, Ta, and W therefore are valuable test cases for studying how materials melt.Despite a large number of experimental and theoretical efforts, however, agreement on the melting behaviour of Mo, Ta, and W at high pressure has been elusive. A number of experimental studies have been carried out with the use of shock-wave measurements [8 -10] and laser-heated diamond-anvil cells [11,12]. Likewise, theoretical studies have attempted to predict the melting curve of Mo, Ta,. Unfortunately, substantial variation exists in the results of these earlier efforts owing to the use of different experimental and theoretical techniques.The above-mentioned discrepancies are illustrated in Fig. 1 for the case of Ta.This figure presents the melting curves reported by different authors [11,12,13,15,18] including a new data point (3850 ± 150 K at 98 GPa) obtained by us using the technique described in Ref. [12]. It shows that at 30 GPa a melting temperature of 3600 ± 100 K was measured using the in situ speckle method [11] and synchrotron x-ray diffraction [12] whereas theoretical calculations [13] and Lindemann estimates [15] give a melting

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Electronic structure of liquid tungsten studied by time-resolved photoelectron spectroscopy

Cited by 14 publications

References 20 publications

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

Melting of aluminum, molybdenum, and the light actinides

Improving the understanding of the melting behaviour of Mo, Ta, and W at extreme pressures

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