Barnard A S, Lin X M, Curtiss L A
Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
J Phys Chem B. 2005 Dec 29;109(51):24465-72. doi: 10.1021/jp054279n.
Many of the unique properties of metallic nanoparticles are determined not only by their finite size but also by their shape, defined by the crystallographic orientation of the surface facets. These surfaces (and therefore the nanoparticles themselves) may differ in a number of ways, including surface atom densities, electronic structure, bonding, chemical reactivities, and thermodynamic properties. In the case of gold, it is known that the melting temperature of nanoparticles strongly depends on the crystal size and that the shape may alter considerably (and yet somewhat unpredictably) during annealing. In this work we use first principle calculations and a thermodynamic model to investigate the morphology of gold nanoparticles in the range 3-100 nm. The results predict that the equilibrium shape of gold nanoparticles is a modified truncated octahedron and that the (size-dependent) melting of such particles is preceded by a significant change in the nanoparticle's morphology.
金属纳米粒子的许多独特性质不仅取决于其有限的尺寸，还取决于其形状，形状由表面小面的晶体取向定义。这些表面（以及纳米粒子本身）可能在许多方面有所不同，包括表面原子密度、电子结构、键合、化学反应性和热力学性质。就金而言，已知纳米粒子的熔化温度强烈依赖于晶体尺寸，并且在退火过程中形状可能会发生相当大的变化（但仍有些不可预测）。在这项工作中，我们使用第一性原理计算和热力学模型来研究3至100纳米范围内金纳米粒子的形态。结果预测，金纳米粒子的平衡形状是一种改良的截顶八面体，并且此类粒子（尺寸依赖性）的熔化之前纳米粒子的形态会发生显著变化。
