Mechanochemistry of One-Dimensional Boron: Structural and Electronic Transitions

Recent production
of long carbyne chains, concurrent with advances
in the synthesis of pure boron fullerenes and atom-thin layers, motivates
an exploration of possible one-dimensional boron. By means of first-principles
calculations, we find two isomers, two-atom wide ribbon and single-atom
chain, linked by a tension-driven (negative-pressure) transformation.
We explore the stability and unusual properties of both phases, demonstrating
mechanical stiffness on par with the highest-performing known nanomaterials,
and a phase transition between stable 1D metal and an antiferromagnetic
semiconductor, with the phase boundary effectively forming a stretchable
1D Schottky junction. In addition, the two-phase system can serve
as a constant-tension nanospring with a well-calibrated tension defined
by enthalpic balance of the phases. Progress in the synthesis of boron
nanostructures suggests that the predicted unusual behaviors of 1D
boron may find powerful applications in nanoscale electronics and/or
mechanical devices.