Melting tungsten nanoparticles: a molecular dynamics study

Abstract

We report a molecular dynamics simulation of melting of tungsten (W) nanoparticles. The modified embedded atom method (MEAM) interatomic potentials are used to describe the interaction between tungsten atoms. The melting temperature of unsupported tungsten nanoparticles of different sizes are found to decrease as the size of the particles decreases. The melting temperature obtained in the present study is approximately a decreasing function of inverse radius, in a good agreement with the predictions of thermodynamic models. We also observed that the melting of a W nanoparticle is preceded by the premelting of its outer skin at a temperature lower than its melting temperature.PACS. 61.46.Df Nanoparticles -61.46.-w Nanoscale materials -64.70.Dv Solid-liquid transitions -65.80.+n Thermal properties of small particles, nanocrystals, and nanotubes

Thermal stability of carbon nanotubes probed by anchored tungsten nanoparticles

“…Thus, we can conclude that a temperature corresponding to the melting point of the W particle was reached at the interface and the CNT did withstand such heating. To estimate this temperature, we used a phenomenological formula [19] relating the melting point T m of a W particle with its diameter R as T m (R) = T * (1 − R 1 /R), where T * is the melting point of bulk tungsten and R l = 2.2 nm is a fitting parameter [19]. Using the values of R = 30 nm and T * ∼ 3700 K [12], we obtain T m ∼ 3400 K. This temperature of CNT up to which it is stable is much higher than those reported previously [7,9] and is close to the theoretical limit [10].…”

Investigation on sintering mechanism of nanoscale tungsten powder based on atomistic simulation

“…Table 3 shows that the results of DFT calculations and experimental values are reproduced satisfactorily by the MEAM parameters for W. In particular, the elastic constants are well matched with the experimental values, although the present MEAM parameters show a tendency to underestimate the bulk modulus and surface energies. This shortcoming causes W nanoparticles to melt at lower temperatures due to premature pre-melting of surface layers [21].…”

“…We have discussed the melting response of bulk and various sizes of nanoparticles from atomistic molecular dynamic simulations more extensively in Ref. [21]. In practice, the isothermal condition of constant NVT simulation would be maintained by immersing nanoparticles in a solvent with a sufficient density such as helium gas to facilitate the heat transfer between the nanoparticles and a heat bath.…”

“…Molecular dynamics (MD) simulations offer a tool to study the melting and coalescence of nanoparticles [19][20][21]. MD simulations of sintering for silicon [22][23][24][25], nickel [26,27], aluminum [28] and titanium dioxide [29][30][31] have been performed extensively to investigate the effect of energy release on the size and shape of particles, phenomenological models and size effects.…”

Atomistic simulations of nanoscale tungsten clusters: From structure and energetics to melting properties

“…Despite the huge progress enabled by these extensive studies, a few atomistic simulations on W clusters have been reported, but the structural details of the W clusters were not presented [20,21]. Though the electronic structure of W nanoscale clusters can be fully captured by DFT calculations, it is computationally demanding for DFT to explore the configurational space and find the global minimum of clusters with hundreds or thousands of atoms.…”