Experiment Verify Calculation on Ideal Strength of Graphene

In 2007, Prof. Ming Pingbing from the CAS Academy of Mathematics and Systems Science and his colleagues made a calculation on the ideal strength of graphene, a promising carbon material. One year later, their work is verified by an experiment that was reported recently in Science.

Graphene, discovered in 2004 by a research team from Manchester University in UK, is a relatively large-scale one-atom thick layer of graphite with remarkable electric characteristics. Experts believe that the nano-transistor made from such a material might greatly raise the operating speed of computers.

The ideal strength refers to the highest achievable strength of a defect-free crystal at 0K. It is a crucial theoretical parameter because it plays a critical role in characterizing the nature of chemical bonding of the crystal. The study of ideal strength can tell us a lot about why some materials are intrinsically brittle, while others are intrinsically ductile.

Via the method of first-principle calculation and teaming up with LIU Fang from the Central University of Finance and Economics in Beijing and LI Ju from the Ohio State University, Ming carried out a careful ab initio study of the ideal tensile strength of flat graphene, as structural motif for carbon nanotubes, nanofibers and other graphene-based materials. The results show that that the value of the monolayer graphene's intrinsic strength is between 110-121GPa, indicating that graphene is the strongest material ever discovered so far.

The results are confirmed by the observation of a research group with the Columbia University in US in the first ever successful experiment to measure the ideal strength of graphene in laboratory. Published by the 18 July issue of Science, the work showed the value was 130±10GPa. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.

Experts say that this show that scientific computation can play a critical role in scientific exploration, including the development of new materials.

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