Size-Dependent Thermodynamic Properties of Metallic Nanowires

Abstract

Analytical models for size-dependent melting temperature Tm(D), melting enthalpy DeltaHm(D), and surface energy gammasv(D) of metallic nanowires have been proposed in terms of the unified nanothermodynamical model where D denotes the diameter of nanowire. As D decreases, Tm(D), DeltaHm(D), and gammasv(D) functions are found to decrease almost with the same size-dependent trend. Due to the inclusion of the effect of dimensionality, the developed model can be applied to other low-dimensional systems. It is found that the ratio of depression of these thermodynamic parameters for spherical nanoparticle, nanowire, and thin film is 3:2:1 when D is large enough (>20h with h being the atomic diameter). The validity of the model is verified by the data of experiments, molecular dynamics simulations, and other theoretical models.

Thermodynamic Imbalance, Surface Energy, and Segregation Reveal the True Origin of Nanotube Synthesis

“…Once the shells are thus formed at the FECA periphery, this FECA may act as a nanocavity. It then follows the predictions by Xiong et al [24] and Lu et al [25] that the surface energy is higher and the melting point lower at the core than at the surface. So, the core is elongated, fragmented and even melted.…”

“…And it is Strikingly, Equation (A7) of the appendix takes into account both positive and negative deviations from the norm. This is reflected from Figure 3(a), where the negative deviation is in close correspondence with the results by Xiong et al [24] and Lu et al [25] But the positive deviation in Figure 3(a) is in close correspondence with the nanoparticle results by Lamber et al, [26] Goldstein et al, [27] Janczuk et al, [28] Berry, [30] Wasserman and Vermaak, [31] and Wasserman et al [32] We argue that the nanotube growth environment may encounter both positive and negative deviations; the negative deviation corresponds to nanocavity, but the positive deviation corresponds to nanoparticle. Figure 3(b) compares the surface energy of the (111) surface of the Fe, Ni, and Ag nanoparticles.…”

“…According to Xiong et al [24] and Lu et al, [25] the surface atoms of a nanoparticle, as compared to those of the bulk of it, have higher tendency to be detached from this nanoparticle. The surface atoms of a nanocavity, as compared to those of a bulk, have, on the other hand, higher tendency to be attached to the nanoparticle.…”

“…Xiong et al [24] indicated that the surface energy of FECA nanoparticles decreases with decreasing FECA size. Based on similar ground, Lu et al [25] suggested that the surface energy of nanowires increases with increasing nanowire diameter. Both of these contradict other findings, which indicate that the surface energy of FECA nanoparticles is larger than that of the corresponding bulk material.…”

In silico determination of surface entropy of 1-D copper nanostructures

“…In addition, a significant surface stress is created, which can even induce elastic nonlinearity in the 1-D systems (Liang et al 2005). Most of the studies on surface relaxation deal with the analysis and computation of surface energies and the energies of relaxation (Diao et al 2004;Ouyang et al 2008;Lu et al 2008). A large fraction of such results are the outcome of first principle calculations and classical atomistic simulations.…”