School of Materials Science and Engineering, UNIST (Ulsan National Institute of Science and Technology), Ulsan, 44919, Republic of Korea.
Center for Electronic Materials, KIST (Korea Institute of Science and Technology), Seoul, 02792, Republic of Korea.
Sci Rep. 2017 Jun 28;7(1):4327. doi: 10.1038/s41598-017-04696-4.
We fabricate nanotubular ZnO with wall thickness of 45, 92, 123 nm using nanoporous gold (np-Au) with ligament diameter at necks of 1.43 μm as sacrificial template. Through micro-tensile and micro-compressive testing of nanotubular ZnO structures, we find that the exponent m in [Formula: see text], where [Formula: see text] is the relative strength and [Formula: see text] is the relative density, for tension is 1.09 and for compression is 0.63. Both exponents are lower than the value of 1.5 in the Gibson-Ashby model that describes the relation between relative strength and relative density where the strength of constituent material is independent of external size, which indicates that strength of constituent ZnO increases as wall thickness decreases. We find, based on hole-nanoindentation and glazing incidence X-ray diffraction, that this wall-thickness-dependent strength of nanotubular ZnO is not caused by strengthening of constituent ZnO by size reduction at the nanoscale. Finite element analysis suggests that the wall-thickness-dependent strength of nanotubular ZnO originates from nanotubular structures formed on ligaments of np-Au.
我们使用纳米孔金（np-Au）作为牺牲模板，制造出壁厚分别为 45、92 和 123nm 的纳米管状 ZnO。通过对纳米管状 ZnO 结构的微拉伸和微压缩测试，我们发现，[Formula: see text]中的指数 m 对于拉伸为 1.09，对于压缩为 0.63，其中[Formula: see text]是相对强度，[Formula: see text]是相对密度。这两个指数都低于 Gibson-Ashby 模型中描述相对强度和相对密度之间关系的 1.5 值，该模型表明组成材料的强度与外部尺寸无关，这表明组成 ZnO 的强度随着壁厚的减小而增加。我们发现，基于孔纳米压痕和玻璃散射 X 射线衍射，纳米管状 ZnO 的这种壁厚相关强度不是由纳米尺度上的尺寸减小引起的组成 ZnO 的强化引起的。有限元分析表明，纳米管状 ZnO 的壁厚相关强度源自 np-Au 连接带上形成的纳米管状结构。
