State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University , Beijing 100871, China.
ACS Nano. 2014 Oct 28;8(10):10246-51. doi: 10.1021/nn5033888. Epub 2014 Sep 29.
Layer-by-layer assembly of graphene has been proven to be an effective way to improve its mechanical properties, but its fracture mechanism, which is crucial for practical device applications, is still not clear and has not been fully studied yet. By consecutive stacking of two graphene monolayers, we fabricate two-layer stacked graphene membranes with a clean interface between the two layers. Fracture behavior of the two-layer stacked graphene membranes is studied using nanoindentation performed by atomic force microscopy. It is found that the fracture force distribution of stacked graphene is very different from that of monolayer graphene. Weibull statistics of fracture forces show that after layer-by-layer stacking of graphene, the membrane becomes less sensitive to the defects during nanoindentation, improving the overall performance of the graphene membranes. Interestingly, a third of our tested membranes show a stepwise fracture, which could serve as a warning message for the mechanical failure of multilayer graphene devices. Our study provides insight into the fracture mechanism of multilayer graphene membranes.
层层组装石墨烯已被证明是提高其机械性能的有效方法，但对于实际器件应用至关重要的其断裂机制仍不清楚，也尚未得到充分研究。通过连续堆叠两层石墨烯，我们制备了具有两层之间干净界面的双层堆叠石墨烯膜。通过原子力显微镜进行的纳米压痕来研究双层堆叠石墨烯膜的断裂行为。结果发现，堆叠石墨烯的断裂力分布与单层石墨烯非常不同。断裂力的威布尔统计表明，在石墨烯层层堆叠之后，膜在纳米压痕过程中对缺陷的敏感性降低，从而提高了石墨烯膜的整体性能。有趣的是，我们测试的三分之一的膜表现出逐步断裂，这可以作为多层石墨烯器件机械失效的警告信号。我们的研究提供了对多层石墨烯膜断裂机制的深入了解。
