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Atomic-scale mechanism of unidirectional oxide growth



Xianhu Sun, Wenhui Zhu, Dongxiang WU, Zhenyu Liu, Xiaobo Chen, Lu Yuan, Guofeng Wang, Renu Sharma, Guangwen Zhou


A fundamental knowledge of the unidirectional growth mechanisms is required for precise control on size, shape, and thereby functionalities of nanostructures. Using transmission electron microscopy that spatially and temporally resolves CuO nanowire growth during the oxidation of copper, here we provide direct evidence of the correlation between unidirectional crystal growth and bicrystal boundary diffusion. Based on atomic scale observations of the upward growth at the nanowire tip and oscillatory downward growth of atomic layers on the nanowire sidewall, we clearly show that bicrystal boundary diffusion is the mechanism by which Cu atoms are delivered from the nanowire root to the tip. Together with density-functional theory calculations, we further show that the asymmetry in the step-crossing barriers promotes the unidirectional oxide growth by hindering the transport of Cu atoms from the nanowire tip to the sidewall facets. We expect broader applicability of our results in manipulating the growth of nanostructured oxides by controlling the bicrystal boundary structure that favors anisotropic diffusion for unidirectional, one-dimensional crystal growth for nanowires or isotropic diffusion for two-dimensional platelet growth.
Advanced Functional Materials


Copper oxide, nanowires, atomic resolution imaging, in situ TEM


Sun, X. , Zhu, W. , WU, D. , Liu, Z. , Chen, X. , Yuan, L. , Wang, G. , Sharma, R. and Zhou, G. (2019), Atomic-scale mechanism of unidirectional oxide growth, Advanced Functional Materials, [online],, (Accessed May 20, 2024)


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Created November 13, 2019, Updated October 12, 2021