High-pressure close-packed structure of boron

Abstract

Based on ab initio evolutionary algorithms, a high-pressure close-packed phase of boron with hexagonal P6₃/mcm symmetry is predicted, named as B₁₀, which is stable over α-Ga phase above 375 GPa to at least 500 GPa. High pressure makes the typical B₁₂ icosahedron collapse to form an incompressible linear atomic chain arrangement together with an isosceles triangle arrangement. The electron localization function calculations confirm that the B₁₀ has strong covalency in this special atomic arranged structure. The vibration of the three atom's isosceles triangle in the framework of linear atomic chains induces an unusual superconductivity in B₁₀. Electron–phonon calculations indicate that electron–phonon coupling parameter λ is 0.82 and the superconducting critical temperature is 44 K at 400 GPa.