Riaz M, Fulati A, Zhao Q X, Nur O, Willander M, Klason P
Department of Science and Technology, Campus Norrköping, Linköping University, SE-60174 Norrköping, Sweden.
Nanotechnology. 2008 Oct 15;19(41):415708. doi: 10.1088/0957-4484/19/41/415708. Epub 2008 Sep 4.
Mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on different substrates including Si, SiC and sapphire (α-Al(2)O(3)) was done quantitatively by the nanoindentation technique. The nanorods were grown on these substrates by the vapor-liquid-solid (VLS) method. The critical load for the ZnO nanorods grown on the Si, SiC and Al(2)O(3) substrates was found to be 188, 205 and 130 µN, respectively. These observed critical loads were for nanorods with 280 nm diameters and 900 nm length using Si as a substrate, while the corresponding values were 330 nm, 3300 nm, and 780 nm, 3000 nm in the case of SiC and Al(2)O(3) substrates, respectively. The corresponding buckling energies calculated from the force displacement curves were 8.46 × 10(-12), 1.158 × 10(-11) and 1.092 × 10(-11) J, respectively. Based on the Euler model for long nanorods and the J B Johnson model (which is an extension of the Euler model) for intermediate nanorods, the modulus of elasticity of a single rod was calculated for each sample. Finally, the critical buckling stress and strain were also calculated for all samples. We found that the buckling characteristic is strongly dependent on the quality, lattice mismatch and adhesion of the nanorods with the substrate.
通过纳米压痕技术定量研究了在包括硅（Si）、碳化硅（SiC）和蓝宝石（α - Al₂O₃）等不同衬底上生长的垂直排列的单晶氧化锌（ZnO）纳米棒的力学不稳定性和屈曲特性。这些纳米棒通过气 - 液 - 固（VLS）方法生长在这些衬底上。发现生长在Si、SiC和Al₂O₃衬底上的ZnO纳米棒的临界载荷分别为188、205和130 μN。这些观察到的临界载荷是针对以Si为衬底、直径280 nm且长度900 nm的纳米棒而言的，而在SiC和Al₂O₃衬底的情况下，相应的直径和长度值分别为330 nm、3300 nm以及780 nm、3000 nm。从力 - 位移曲线计算出的相应屈曲能量分别为8.46×10⁻¹²、1.158×10⁻¹¹和1.092×10⁻¹¹ J。基于长纳米棒的欧拉模型和中间纳米棒的J B约翰逊模型（它是欧拉模型的扩展），计算了每个样品中单个纳米棒的弹性模量。最后，还计算了所有样品的临界屈曲应力和应变。我们发现屈曲特性强烈依赖于纳米棒与衬底的质量、晶格失配和附着力。
