Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong, China.
Centre of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China.
Science. 2018 Apr 20;360(6386):300-302. doi: 10.1126/science.aar4165.
Diamonds have substantial hardness and durability, but attempting to deform diamonds usually results in brittle fracture. We demonstrate ultralarge, fully reversible elastic deformation of nanoscale (~300 nanometers) single-crystalline and polycrystalline diamond needles. For single-crystalline diamond, the maximum tensile strains (up to 9%) approached the theoretical elastic limit, and the corresponding maximum tensile stress reached ~89 to 98 gigapascals. After combining systematic computational simulations and characterization of pre- and postdeformation structural features, we ascribe the concurrent high strength and large elastic strain to the paucity of defects in the small-volume diamond nanoneedles and to the relatively smooth surfaces compared with those of microscale and larger specimens. The discovery offers the potential for new applications through optimized design of diamond nanostructure, geometry, elastic strains, and physical properties.
钻石具有较大的硬度和耐久性，但通常试图改变钻石的形状会导致脆性断裂。我们展示了纳米级（约 300 纳米）单晶和多晶金刚石针的超大、完全可逆的弹性变形。对于单晶金刚石，最大拉伸应变（高达 9%）接近理论弹性极限，相应的最大拉伸应力达到约 89 到 98 吉帕斯卡。通过系统的计算模拟和对预变形和后变形结构特征的分析，我们将高强度和大弹性应变归因于小体积金刚石纳米针中缺陷的稀少，以及与微尺度和更大尺寸的样品相比相对光滑的表面。这一发现为通过优化金刚石纳米结构、几何形状、弹性应变和物理性能来设计新的应用提供了可能。
