Superconducting boron allotrope featuring pentagonal bipyramid at ambient pressure

Abstract

Elemental boron has evoked substantial interestbecause of its chemical complexity in nature. It can form multicenter bonds due to its electron deficiency, which induces the formation of various stable and...

Theoretical Design of Strengthened Nanotwinned γ*-Boron

“…Boron possesses a range of complex polymorphs with abundant properties, on account of intrinsic electron deficiency and flexible bonding modes of the boron atom, that have garnered considerable attention in the physical science fields. Extensive research efforts have been dedicated to experimental synthesis and theoretical prediction of various stable and metastable boron structures. − Among these structures, α-B 12 and β-B 106 exhibit close static energy as competitive ground-state phases at ambient conditions, , with α-B 12 becoming more stable than β-B 106 at low temperatures as pressure increases. , At pressures exceeding 10 GPa and temperatures above 1500 °C, the orthorhombic phase γ-B 28 has been observed, which can be quenched to ambient conditions. , These structures of boron comprise icosahedral B 12 cages with intracage and intercage two- or three-center bonds, in which strong covalent bonding configurations render elemental boron as candidate superhard crystals. Notably, the γ-B 28 phase adopts a NaCl-type arrangement, with icosahedral B 12 clusters at the vertex and dumbbell B 2 pairs at the face center .…”