Load-induced dynamical transitions at graphene interfaces
Load-induced dynamical transitions at graphene interfaces
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DOI：
10.1073/pnas.1922681117
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发表时间：
2020-06-09
影响因子：
11.1
通讯作者：
Zheng, Quanshui
中科院分区：
文献类型：
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作者：
Peng, Deli;Wu, Zhanghui;Zheng, Quanshui
自2012年在微尺度石墨中实现结构超润滑以来，结构超润滑（SSL）即两个接触固体表面之间的摩擦接近于零的状态引起了人们越来越多的研究兴趣。一个明显的问题是SSL对微纳米级器件（如致动器）的影响。最简单的致动器是基于施加法向载荷;在这里，我们表明这会导致微尺度石墨台面中显着的动力学现象。在一个不断增加的正常负载下，我们观察到机械不稳定性导致的动态状态，第一个加载梅萨突然eerados一个薄片和第二个特征在于奇特的振荡，在此期间，一片反复弹出的梅萨和缩回。测得的弹射速度非常高（最大为294 m/s），对应于超高加速度（最大为1.1x1010 m/s（2））。这些意见合理化使用一个简单的模型，考虑到SSL的石墨接触和样品的微观结构，并考虑之间的竞争的弹性和界面能，定义的动态相图的系统。通过分析观察到的片状喷射和振荡，我们得出结论，与文献报道的相比，我们的系统在SSL中具有高速度，低摩擦系数为3.6 × 10（-6），高品质因子为1.3 × 10（7）。我们的实验发现和理论研究结果表明，发展的SSL为基础的设备，如高频率振荡器的高品质因数和光机械开关，其中可伸缩或振荡镜是必需的。
The structural superlubricity (SSL), a state of near-zero friction between two contacted solid surfaces, has been attracting rapidly increasing research interest since itwas realized in microscale graphite in 2012. An obvious question concerns the implications of SSL for micro- and nanoscale devices such as actuators. The simplest actuators are based on the application of a normal load; here we show that this leads to remarkable dynamical phenomena in microscale graphite mesas. Under an increasing normal load, we observe mechanical instabilities leading to dynamical states, the first where the loaded mesa suddenly ejects a thin flake and the second characterized by peculiar oscillations, during which a flake repeatedly pops out of the mesa and retracts back. Themeasured ejection speeds are extraordinarily high (maximum of 294 m/s), and correspond to ultra-high accelerations (maximum of 1.1x1010 m/s(2)). These observations are rationalized using a simple model, which takes into account SSL of graphite contacts and sample microstructure and considers a competition between the elastic and interfacial energies that defines the dynamical phase diagram of the system. Analyzing the observed flake ejection and oscillations, we conclude that our system exhibits a high speed in SSL, a low friction coefficient of 3.6x10(-6), and a high quality factor of 1.3x10(7) compared with what has been reported in literature. Our experimental discoveries and theoretical findings suggest a route for development of SSL-based devices such as high-frequency oscillators with ultrahigh quality factors and optomechanical switches, where retractable or oscillating mirrors are required.