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arXiv 0908.3004cond-mat.mtrl-sci
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失配位错介导的异质外延岛扩散

Misfit-Dislocation-Mediated Heteroepitaxial Island Diffusion

A. W. Signor, Henry H. Wu, Dallas R. Trinkle

摘要:

扫描隧道显微镜结合分子动力学模拟揭示了Cu在Ag(111)上的位错介导的岛状扩散机制。簇运动跟踪原子精度在多个温度和扩散障碍和前因子从直接测量的跳跃率。的扩散势垒的非单调的大小依赖性是在很好的协议与模拟,并可以导致增强的质量输运粗化后,在令人惊讶的对比传统的岛扩散模型,其中扩散率随团簇大小降低。

英文摘要:

Scanning tunneling microscopy combined with molecular dynamics simulations reveal a dislocation-mediated island diffusion mechanism for Cu on Ag(111), a highly mismatched system. Cluster motion is tracked with atomic precision at multiple temperatures and diffusion barriers and prefactors are determined from direct measurements of hop rates. The non-monotonic size dependence of the diffusion barrier is in good agreement with simulations and can lead to enhanced mass transport upon coarsening, in surprising contrast to the traditional island diffusion models where diffusivity reduces with cluster size.

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