Three metallic BN polymorphs: 1D multi-threaded conduction in a 3D network.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Boron nitride (BN) is known for its diverse properties, but metallic polymorphs with sp2/sp3 hybridization are less explored.
• Understanding the relationship between atomic structure and electronic properties in BN is crucial for developing new materials.

Purpose of the Study:

• To propose and characterize novel metallic sp2/sp3-hybridized boron nitride (BN) polymorphs.
• To investigate the structural stability and electronic properties of these predicted BN phases.
• To elucidate the mechanism behind the observed metallicity in the proposed structures.

Main Methods:

• First-principles calculations, including evolutionary particle swarm structural search.
• Stability analysis using density of states and electron orbital calculations.
• Manual construction of BN structures based on structure-property relationships.

Main Results:

• Three novel metastable metallic sp2/sp3-hybridized BN polymorphs were successfully proposed.
• One polymorph, tP-BN, features a tube-like 3D network with 1D linear conductive channels.
• The metallicity in tP-BN originates from sp2-hybridized B and N atoms, confirmed by electronic structure calculations.
• Two additional manually constructed BN structures also exhibit 1D conductive channels along different axes.

Conclusions:

• The study introduces new metallic BN structures, expanding the known phase diagram of boron nitride.
• The findings highlight the potential of sp2/sp3-hybridized BN for conductive applications.
• This work provides a deeper understanding of conductive mechanisms in BN compounds.