James Tour of Rice University and colleagues at the University of California at Berkeley and the Lawrence Berkeley National Laboratory used potassium and temperatures of 300 °C to split boron nitride nanotubes along their lengths. This easy, scalable synthesis technique results in narrow (as small as 20 nm in size), highly crystalline boron nitride nanoribbons (BNNRs) with uniform widths. The ribbons are at least 1 µm long and have few defects both in the plane and along the ribbon edges.

Boron nitride nanotubes are the boron nitride structural equivalent of graphene nanoribbons (GNRs) and, like their graphene counterparts, are also expected to have unique electronic and magnetic properties depending on their various edge structures. BNNRs could find use in spintronics and optoelectronics applications, for example.

High-quality BNNRs
Until now, however, scientists did not have good-quality BNNRs on which to experiment and test these properties. This is because there was no reliable way of making high-quality ribbons from boron nitride. "With our simple preparation technique it may now be possible for us to find out what kind of good properties BNNRs actually do have," team members Alex Sinitskii and Kris Erickson told nanotechweb.org.

BNNRs themselves are also ideal substrates for "wonder material" graphene because they do not contain defects in which graphene electrons can become trapped. This ensures that graphene's exceptionally high electron mobility remains high. "BNNRs are dielectrics while GNRs are conductors or semiconductors depending on their width," said Tour. "But BNNRs make great complements to graphene as surfaces on which the material can be grown."

The team now hopes to make even higher quality BNNRs and tailor the edges for spintronics applications. It also plans to make devices from the ribbons and characterize the edge structures of the materials.

The work was reported in Nano Letters.