Build Borophite from Borophenes: A Boron Analogue Graphite.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Borophenes are synthetic 2D boron materials, unlike graphite, lacking bulk allotropes and exhibiting covalent bonding.
• Van der Waals (vdW) stacking is typical for layered materials like graphite, but not inherent to borophenes.

Purpose of the Study:

• To investigate the potential for bulk-layered boron allotropes via vdW stacking of boron bilayers.
• To identify boron structures that could mimic graphite's layered structure.

Main Methods:

• Systematic high-throughput screening of 665 vdW-stacking boron bilayers.
• Stability analysis of identified boron bilayer structures.
• Electronic and topological structure analysis of promising candidates.

Main Results:

• Most boron bilayers showed a preference for covalent bonding, not vdW stacking.
• δ5 borophene emerged as a stable vdW-stacking candidate.
• δ5 borophene analogues are metallic and exhibit phonon-mediated superconductivity near 22 K.

Conclusions:

• The study introduces the concept of "borophite", a potential bulk-layered boron allotrope analogous to graphite.
• δ5 borophene and its analogues offer a pathway towards designing novel vdW-stacked boron materials with unique electronic properties.