We have analysed the expressed manifestation of the anisotropy of surface energy density in the dynamics of ultrathin nanowires, which break up into disjointed clusters when annealed below their melting temperature. The breakup process is studied for different temperatures and orientations of the nanowire axis relative to its internal crystal structure using the Monte Carlo kinetic method. We have also presented an approximate analytical model of the instability of nanowires. Generally, the interpretation of experimental results refers to the theoretical model developed by Nichols and Mullins, which is based on conceptions about the Rayleigh instability of liquid jets. In both cases, the theories – which do not take into account the anisotropy of surface energy density – predict the breakup of a nanowire/liquid jet with radius r into fragments with an average length Λ = 9r. However, the observed value, Λ/r, often deviates from 9 either to lower values or to substantially greater ones (up to 24–30). Our results explain various observed features of the breakup and the significant variations in the values of its parameter Λ/r depending on experimental conditions. In particular, the ambiguous role of exchange by atoms of the surface of a nanowire with a surrounding layer of free atoms formed as a result of their rather intensive sublimation, which occurs in a number of cases, has been investigated. We have shown that this exchange can lead both to a decrease and to a significant increase in the parameter Λ/r. The obtained results could be potentially useful in applications such as the development of optical waveguides based on ordered nanoparticle chains.

中文翻译：

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金属FCC纳米线分解成有序的纳米液滴链中的各向异性效应的多样性

我们已经分析了超薄纳米线动力学中表面能密度各向异性的表现形式，当在低于其熔化温度的温度下退火时，其分解成不相交的簇。使用蒙特卡罗动力学方法研究了纳米线轴相对于其内部晶体结构的不同温度和取向的破裂过程。我们还提出了纳米线不稳定性的近似分析模型。通常，对实验结果的解释是指由Nichols和Mullins开发的理论模型，该模型基于有关液体射流瑞利不稳定性的概念。在这两种情况下，这些理论（均未考虑表面能密度的各向异性）可预测纳米线/液体射流的半径破裂r分为平均长度Λ = 9 r的片段。但是，观测值Λ / r经常从9偏离到较低的值或基本上偏离较大的值（直到24–30）。我们的结果解释了破裂的各种观察到的特征及其参数Λ / r值的显着变化取决于实验条件。特别地，已经研究了纳米线表面的原子与由于在许多情况下发生的相当强烈的升华而形成的周围的自由原子的周围层交换的模棱两可的作用。我们已经表明，这种交换既可以导致参数Λ / r减小，也可以导致其显着增大。获得的结果可能在诸如基于有序纳米粒子链的光波导的开发等应用中可能有用。