posted on 2024-03-07, 05:03authored byNan Min, Di Wang, Zikai Liu, Xianqi Song, Xing Meng, Quan Li
The distinctive electron deficiency and unusual multicenter
bonding
situations of boron give rise to fascinating chemical complexity and
imaginative structural polymorphism. Herein, we employ an independently
developed method to construct the new twinned γ*-boron based
on the well-known hardest elemental boron, γ-B28.
Notably, the newly propounded γ*-boron phases exhibit considerably
close energy levels with γ-B28 under ambient conditions.
The simulated X-ray diffraction patterns of stable twinned structure
present excellent agreement with experimental data. First-principles
calculations reveal a 7.5% increase in the ideal Vickers shear strength
of γ*-boron compared to γ-B28, attributed to
diverse bond responses within the twinned slabs. The evaluated hardness
of nanotwinned γ*-B reaches 59 GPa in consideration of the size
hardening effect. Our research presents an efficient strategy for
constructing new polymorphs of boron with improved mechanical properties
and expands the knowledge about twinning structures of boron.