Mu Yuewen, Wang Bao-Tian, Li Si-Dian, Ding Feng
Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province, Institute of Molecular Science, Shanxi University, Taiyuan, 030006, China.
Spallation Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Dongguan, Guangdong 523803, China.
Nanoscale. 2022 Jul 14;14(27):9754-9761. doi: 10.1039/d2nr02013k.
Monolayer borophenes tend to be easily oxidized, while thicker borophenes have stronger antioxidation properties. Herein, we proposed four novel metallic boron crystals by stacking the experimentally synthesized borophenes, and one of the crystals has been reported in our previous experiments. Bilayer units tend to act as blocks for crystals as determined by bonding analyses. Their kinetic, thermodynamic and mechanical stabilities are confirmed by our calculated phonon spectra, molecular dynamics and elastic constants. Our proposed allotropes are more stable than the boron α-Ga phase below 1000 K at ambient pressure. Some of them become more stable than the α-rh or γ-B phases at appropriate external pressure. More importantly, our calculations show that three of the proposed crystals are phonon-mediated superconductors with critical temperatures of about 5-10 K, higher than those of most superconducting elemental solids, in contrast to typical boron crystals with significant band gaps. Our study indicates a novel preparation method for metallic and superconducting boron crystals dispensing with high pressure.
单层硼烯容易被氧化，而较厚的硼烯具有更强的抗氧化性能。在此，我们通过堆叠实验合成的硼烯提出了四种新型金属硼晶体，其中一种晶体已在我们之前的实验中报道。通过键合分析确定，双层单元倾向于作为晶体的结构单元。我们通过计算声子谱、分子动力学和弹性常数证实了它们的动力学、热力学和机械稳定性。在环境压力下，我们提出的同素异形体在1000 K以下比硼的α-Ga相更稳定。其中一些在适当的外部压力下比α-rh或γ-B相更稳定。更重要的是，我们的计算表明，所提出的三种晶体是声子介导的超导体，临界温度约为5-10 K，高于大多数超导元素固体，这与具有显著带隙的典型硼晶体形成对比。我们的研究表明了一种无需高压制备金属和超导硼晶体的新方法。
