This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Since the production of graphene in 2004, two-dimensional materials have been sparking scientific and technological interest. As they are only a few atomic layers thick, or even just a single atomic layer, they can exhibit special electronic, magnetic or chemical properties—which make them particularly interesting for applications such as electronics, catalysis and energy storage.
The best-known examples are formed from so-called van der Waals crystals. Just like a book, they are composed of individual layers held together by comparatively weak forces. It is therefore relatively easy to peel off individual layers.
In nonlayered crystals, on the other hand, the atoms form a three-dimensional network of significantly stronger bonds. Until now, it has been difficult to predict which of these solids could be split into stable layers. "Given that this class of materials is still so young, selecting suitable materials for experiments was often based on experience and intuition," explains Dr.
Rico Friedrich of HZDR's Institute of Ion Beam Physics and Materials Research and TU Dresden. "Using our universal method, we can now determine the points at which a crystal in any material can best be split and whether a potentially stable two-dimensional structure can form in the process." The core of the new approach, now published in Nature Communications, is the eXfoliation and Cleavage Potential, or XCP, for short. The computational model uses the chemical elements involved and the distance between them to calculate precisely the strength of the bonds between individual atoms.
Two additional algorithms subsequently search either for easily separable crystal planes or gradually remove the weakest bonds from the model until two-dimensional substructures remain. By doing so, the method also detects atomically uneven separation surfaces. "Calculating the electronic structure for every conceivable surface would be incredibly time-consuming," says the lead author, Tom Barnowsky.
"Our efficient model, on the other hand, can search big materials databases with minimal computational effort. Detailed calculations are only required for particularly promising hits." Wide-ranging tests on two-dimensional materials already produced experimentally have shown that the XCP method can reliably determine the preferred exfoliable planes. It is also freely available to interested parties as a web tool.
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