Coalescence is a phenomenon in which two or more nanoparticles merge to form a single larger aggregate. By means of gas-phase magnetron-sputtering aggregation experiments on Pt–Pd nanoalloys, it is shown that the degree of coalescence can be tuned from a growth regime in which coalescence is negligible to a regime where the growth outcome is dominated by coalescence events. This transition is achieved by varying both the length of the aggregation zone and the pressure difference between the aggregation and the deposition chamber. In the coalescence-dominated regime, a wide variety of coalescing aggregates is produced and analyzed by TEM. The experimental results are interpreted with the aid of molecular-dynamics simulations. This allows to distinguish four different steps through which coalescence proceeds towards equilibrium. These steps, occurring on a hierarchy of well-separated time scales, consist in: (i) alignment of atomic columns; (ii) alignment of close-packed atomic planes; (iii) equilibration of shape; (iv) equilibration of chemical ordering.

中文翻译：

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调整 Pt-Pd 纳米合金生长过程中的聚结度

聚结是两个或多个纳米粒子合并形成单个较大聚集体的现象。通过对 Pt-Pd 纳米合金进行气相磁控溅射聚集实验，表明聚结程度可以从聚结可忽略不计的生长状态调整到生长结果由聚结事件主导的状态。这种转变是通过改变聚集区的长度和聚集区和沉积室之间的压力差来实现的。在以聚结为主的状态下，通过 TEM 产生和分析了各种各样的聚结聚集体。借助分子动力学模拟来解释实验结果。这允许区分四个不同的步骤，通过这些步骤聚结朝着平衡前进。这些步骤，发生在分离良好的时间尺度的层次结构上，包括： (i) 原子列的对齐；(ii) 排列紧密的原子平面；(iii) 形状平衡；(iv) 化学排序的平衡。