Researchers try to control defects by growing atom-thin sheets on cones

Source:Xinhua Published: 2017/8/10 9:29:09

Researchers have learned to manipulate two-dimensional materials to design in defects that enhance the materials' properties.

According to news release by Rice University of Texas on Wednesday, Rice lab of theoretical physicist Boris Yakobson and colleagues at Oak Ridge National Laboratory are combining theory and experimentation to prove it's possible to give 2-D materials specific defects, especially atomic-scale seams called grain boundaries.

These boundaries may be used to enhance the materials' electronic, magnetic, mechanical, catalytic and optical properties.

Grain boundaries are the borders that appear in a material where edges meet in a mismatch. These boundaries are a series of defects; for example, when two sheets of hexagonal graphene meet at an angle, the carbon atoms compensate for it by forming nonhexagonal (five- or seven-member) rings.

Yakobson and his team have already demonstrated that these boundaries can be electronically significant. They can, for instance, turn perfectly conducting graphene into a semiconductor.

The key is introducing curvature to the landscape that constrains the way defects propagate. The researchers call this "tilt grain boundary topology," and they achieve it by growing their materials onto a topographically curved substrate - in this case, a cone. The angle of the cone dictates if, what kind and where the boundaries appear.

Rice graduate students Henry Yu and Nitant Gupta are co-lead authors of the paper. And the research is the subject of a paper in the American Chemical Society journal ACS Nano.

The US Department of Energy Basic Energy Sciences and its Center for Nanophase Materials Sciences and the Office of Naval Research supported the research.

Posted in: BIOLOGY

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