School of Physics and CRANN, Trinity College, Dublin 2, Ireland.
Nanoscale. 2017 Apr 20;9(16):5205-5211. doi: 10.1039/c7nr00095b.
Crystalline aluminum oxide is a brittle ceramic material. Here we show that individual alumina nanotubes with internal and external radii of ∼15 nm and ∼50 nm, respectively and lengths of the order of 100 μm can be readily separated from amorphous alumina membranes fabricated by a hard anodisation process under a magnetic field of up to 1.5 T. The ceramic nanotubes are extremely flexible and exhibit an exceptional plasticity of ±70% at room temperature without breaking. Elastic properties investigated by the double clamped beam method include a tensile strength of 4.1 GPa, corresponding to a breaking strain of 5%. These values are respectively 17 and 70 times greater than those of polycrystalline alumina fibres. The plasticity of anodic amorphous alumina helps explain the formation of ordered arrays of nanopores in the alumina membranes.
结晶氧化铝是一种脆性陶瓷材料。在这里，我们展示了可以通过在磁场下进行硬质阳极氧化处理来制备非晶态氧化铝膜，然后从中分离出直径约为 15nm 和 50nm、长度约为 100μm 的氧化铝纳米管。这种陶瓷纳米管非常柔韧，在室温下可以实现 70%的超弹性变形而不断裂。通过双悬臂梁法测量的弹性性能包括 4.1GPa 的拉伸强度，对应 5%的断裂应变。这些值分别比多晶氧化铝纤维大 17 倍和 70 倍。阳极非晶氧化铝的塑性有助于解释氧化铝膜中纳米孔有序排列的形成。
