NUS Graduate School for Integrative Sciences and Engineering, Singapore.
Nanotechnology. 2011 Jun 10;22(23):235606. doi: 10.1088/0957-4484/22/23/235606. Epub 2011 Apr 12.
In this work, we show how the vacancy diffusion length scale must be considered, in the context of the diameter of a nanowire, when utilizing the Kirkendall phenomenon in the fabrication of metal oxide nanotubes starting from metal nanowires. We find that the diameter of the nanowire relative to the diffusion length scale of the vacancy will affect greatly the type of voids that can be generated. By using a larger diameter nickel nanowire, we show that segmented heterojunction void formation can be avoided and that the resulting structure will serve as a precursory 'template' for subsequent oxidation processes at high temperatures. In doing so, we can prevent the formation of bamboo-like structures and obtain uniform nickel oxide nanotubes through direct oxidation that has proven to be difficult previously. The result from this work is also significant as the interplay of vacancy diffusion length and nanostructure dimension is important in the oxidation of other types of metal nanostructures, especially when void formation and the Kirkendall effect are involved.
在这项工作中，我们展示了当利用 Kirkendall 现象从金属纳米线制造金属氧化物纳米管时，必须考虑空位扩散长度尺度与纳米线直径之间的关系。我们发现，纳米线的直径相对于空位的扩散长度尺度会极大地影响可以产生的空隙类型。通过使用更大直径的镍纳米线，我们表明可以避免分段异质结空隙的形成，并且所得结构将作为随后在高温下进行氧化过程的前驱“模板”。这样，我们可以防止竹状结构的形成，并通过以前证明难以实现的直接氧化获得均匀的氧化镍纳米管。这项工作的结果也很重要，因为空位扩散长度和纳米结构尺寸的相互作用在其他类型的金属纳米结构的氧化中很重要，特别是当涉及到空隙形成和 Kirkendall 效应时。
