Polymorphism of low dimensional boron nanomaterials driven by electrostatic gating: a computational discovery

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) boron sheets are typically synthesized on silver surfaces, which provide electrostatic gating.
• The influence of electrostatic gating on the structures of one-dimensional (1D) boron remains largely unexplored.

Purpose of the Study:

• To investigate the structural transformations of boron under electrostatic gating.
• To discover new 1D boron structures and understand their stability.
• To identify suitable substrates for fabricating novel boron materials.

Main Methods:

• Unbiased global minimum structure search.
• Density functional theory (DFT) computations.
• Analysis of boron structures at varying excess charge densities.

Main Results:

• Coexistence of 2D boron sheets and 1D boron ribbons is induced by electrostatic gating.
• Low charge density favors 2D sheets, while higher charge density promotes 1D ribbons.
• A stable, flat borophene-like ribbon (FBR) with high mechanical strength was discovered.
• The electride Ca2N was identified as an ideal substrate for FBR fabrication.

Conclusions:

• Electrostatic gating enables the transition between 2D and 1D boron structures.
• Polymorphism of 1D boron ribbons under gating is revealed.
• Findings provide insights for synthesizing and applying low-dimensional boron materials.