International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
Nanoscale. 2013 Jun 7;5(11):4840-6. doi: 10.1039/c3nr00651d. Epub 2013 Apr 24.
Bending manipulation and direct force measurements of ultrathin boron nitride nanotubes (BNNTs) were performed inside a transmission electron microscope. Our results demonstrate an obvious transition in mechanics of BNNTs when the external diameters of nanotubes are in the range of 10 nm or less. During in situ transmission electron microscopy bending tests, characteristic "hollow" ripple-like structures formed in the bent ultrathin BNNTs with diameters of sub-10 nm. This peculiar buckling/bending mode makes the ultrathin BNNTs hold very high post-buckling loads which significantly exceed their initial buckling forces. Exceptional compressive/bending strength as high as ∼1210 MPa was observed. Moreover, the analysis of reversible bending force curves of such ultrathin nanotubes indicates that they may store/adsorb strain energy at a density of ~400 × 10(6) J m(-3). Such nanotubes are thus very promising for strengthening and toughening of structural ceramics and may find potential applications as effective energy-absorbing materials like armor.
在透射电子显微镜内对超薄氮化硼纳米管（BNNTs）进行了弯曲操作和直接力测量。我们的结果表明，当纳米管的外径在 10nm 或以下时，BNNTs 的力学性能会发生明显的转变。在原位透射电子显微镜弯曲测试中，具有亚 10nm 直径的弯曲超薄 BNNTs 中形成了特征性的“空心”波纹状结构。这种特殊的屈曲/弯曲模式使超薄 BNNTs 能够承受非常高的后屈曲载荷，远远超过其初始屈曲力。观察到高达约 1210MPa 的异常抗压/弯曲强度。此外，对这种超薄纳米管的可逆弯曲力曲线的分析表明，它们可能以约 400×10(6)J m(-3)的密度存储/吸附应变能。因此，这些纳米管有望增强和增韧结构陶瓷，并可能作为有效的吸能材料，如装甲，具有潜在的应用前景。
