title: Coexistence of Superconductivity and Superhardness in Beryllium Hexaboride Driven by Inherent Multicenter Bonding.
abstract: Unique multicenter bonding in boron-rich materials leads to the formation of complex structures and intriguing properties. Here global structural searches are performed to unearth the structure of beryllium hexaboride (BeB6) synthesized decades ago. Three BeB6phases (α, β, and γ) were predicted to be stable at ambient and high pressures. The ground state at ambient pressure, α-BeB6, consists of a strong and uniformly distributed covalent B-B network, which results in exceptional elastic properties and a hardness of 46 GPa comparable to γ-B. Even more surprisingly, α-BeB6retains credible electron phonon coupling in the boron sublattice, and is predicted to be superconducting at 9 K. Above 4 GPa, β-BeB6is stabilized with alternating boron slabs and triangular beryllium layers analogous to the structure of MgB2. The β-BeB6is predicted to be superconducting at 24 K, similar to Nb3(Al,Ge). The γ-BeB6is stable above 340 GPa. The understanding of intrinsic multicenter-bonding mechanism and related properties demonstrated in the very example of BeB6provides new insights for the design of tunable multifunctional materials.
authors.affiliation: Key Laboratory of Metastable Materials Science and Technology, College of Material Science and Engineering, Yanshan University , Qinhuangdao 066004, China.
authors.forename: Lailei
authors.initials: L
authors.lastname: Wu
authors.affiliation: Key Laboratory of Metastable Materials Science and Technology, College of Material Science and Engineering, Yanshan University , Qinhuangdao 066004, China.|Center for High Pressure Science and Technology Advanced Research , Beijing 100094, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Wan
authors.affiliation: Geophysical Laboratory, Carnegie Institution of Washington , 5251 Broad Branch Road NW, Washington, D.C. 20015, United States.
authors.forename: Hanyu
authors.initials: H
authors.lastname: Liu
authors.affiliation: Center for High Pressure Science and Technology Advanced Research , Beijing 100094, China.|Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University , Qinhuangdao 066004, China.
authors.forename: Huiyang
authors.initials: H
authors.lastname: Gou
authors.affiliation: Department of Physics and Engineering Physics, University of Saskatchewan , Saskatoon, Saskatchewan S7N 5E2, Canada.|Canadian Light Source , Saskatoon, Saskatchewan S7N 2V3, Canada.
authors.forename: Yansun
authors.initials: Y
authors.lastname: Yao
authors.affiliation: Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University , Qinhuangdao 066004, China.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Li
authors.affiliation: Key Laboratory of Metastable Materials Science and Technology, College of Material Science and Engineering, Yanshan University , Qinhuangdao 066004, China.
authors.forename: Jingwu
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University , Qinhuangdao 066004, China.
authors.forename: Faming
authors.initials: F
authors.lastname: Gao
authors.affiliation: Center for High Pressure Science and Technology Advanced Research , Beijing 100094, China.|Geophysical Laboratory, Carnegie Institution of Washington , 5251 Broad Branch Road NW, Washington, D.C. 20015, United States.
authors.forename: Ho-Kwang
authors.initials: HK
authors.lastname: Mao