Computer simulations of the effect of atomic structure and coordination on the stabilities and melting behaviour of copper surfaces and nano-particles
Computer simulations of the effect of atomic structure and coordination on the stabilities and melting behaviour of copper surfaces and nano-particles
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DOI：
10.1016/j.susc.2008.11.031
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发表时间：
2009-02-01
期刊：
影响因子：
1.9
通讯作者：
de Leeuw, Nora H.
中科院分区：
文献类型：
--
作者：
Daff, Thomas D.;Saadoune, Iman;de Leeuw, Nora H.
我们已经研究了铜纳米颗粒的结构和稳定性和铜表面的熔化特性，使用基于原子间势的分子动力学模拟，其中（111）表面已被证明是最稳定的表面能和熔化行为。纳米颗粒的低能形状受表面的影响，因此具有较高的（111）表面比例。随着纳米颗粒尺寸的增大，表面结构对稳定性的影响变得不那么显著。在所有研究的表面中，在从（111）、（100）、（110）到（210）表面的逐渐降低的温度下，观察到熔融在低于本体熔融温度下发生，证实了它们的稳定性降低的顺序。模拟了缺陷密集铜表面的熔化过程。台阶、扭结和刻面都被证明加速了表面的熔化。结果表明，在较低的温度下，在台阶边缘或扭结处的低配位原子具有更强的移动的性。这些特征有助于表面熔化，甚至比完美表面所观察到的熔化温度更低。此外，（100）面的小面被证明是不稳定的，即使在中等温度下的紧密堆积的表面上。(C)2008 Elsevier B.V.保留所有权利。
We have studied the structures and stabilities of copper nano-particles and the melting properties of copper surfaces using interatomic potential-based molecular dynamics simulations, where the (111) surface has been shown to be the most stable in terms of surface energy and melting behaviour. Low energy shapes of nano-particles are influenced by the surfaces present and therefore have a higher proportion Of (111) Surface. The effect of surface structure on stability becomes less marked as the size of the nano-particle is increased. Melting is observed to occur below the bulk melting temperature in all the surfaces investigated, at increasingly lower temperatures from the (111), (100), (110) down to the (210) surface, confirming their order of decreasing stability. The melting processes of defective close-packed copper surfaces were also simulated. Steps, kinks, and facets were all shown to accelerate the melting of the surfaces. The melting is shown to initiate at the site of the defect and the results demonstrate that it is the low-coordinated atoms, at the step edge or kink, that ire more mobile at lower temperatures. These features facilitate surface melting even further below the melting temperature than was observed for the perfect surfaces. Furthermore, facets of (100) surface were shown to be unstable even at moderate temperatures on the close-packed surface. (C) 2008 Elsevier B.V. All rights reserved.