新型二维纳米材料—硼烯的力学、电学性质及其调控特性的第一原理研究

At the end of 2015, the successful synthesis of two-dimensional (2D) nanomaterial of pure boron, borophene, was a remarkable breakthrough in the research field of 2D nanomaterials. The particular atomic-scale corrugation of borophene results in the strong anisotropy both in mechanical and electrical properties. Thus, borophene possesses more diversity in the performance modulation methods than other 2D nanomaterials. Considering the significant lack of research works on the mechanical and electrical properties of borophene, this project will use the first-principles calculations to investigate the intrinsic anisotropy of mechanical and electrical properties of free-standing borophene without the constraint of substrates. The anisotropic deformation and fracture behaviors of borophene in different directions will be systemically studied as well. By applying external load along different directions, the strain engineering of anisotropic electrical properties of borophene will be clarified. In addition, different interface models between borophene and four typical metallic substrates will be established, and the substrate effect on the structural stability, mechanical and electrical properties of borophene will be investigated. Furthermore, the microscopic mechanism of external load and substrate effects on mechanical and electrical properties of borophene will be studied from atomic and electronic points of view. Outputs of the project are believed to be beneficial for scientific understanding of borophene and thus facilitating their synthesis and practical applications.

在2015年底成功制备出的纯硼二维纳米材料——硼烯是二维纳米材料研究领域的一个重要突破。硼烯材料特殊的原子尺度褶皱结构使其力学与电学性能均为各向异性，因此，硼烯具备了比其它二维纳米材料更为丰富的性能调控特性。针对硼烯的力学和电学特性研究显著不足的现状，本项目将利用第一原理计算的方法研究无基体约束的自由硼烯材料各向异性的本征力学和电学特性，系统分析其变形与破坏等关键力学行为。并通过施加不同方向的外部载荷，明确硼烯各向异性电学性质的应变调控特性。建立硼烯与典型金属基体材料的界面模型，研究基体材料对硼烯结构稳定性、力学和电学特性等的影响规律。同时，本研究将进一步从原子及电子层面分析外部载荷和基体材料对硼烯力学和电学性能调控的微观物理机制。本研究具有重要的科学意义，也为新型二维硼烯材料制备方法的改进及其在高性能纳米电子器件中的应用提供重要的理论依据。

二维硼烯材料独特的各向异性力学和电学性质受到了研究人员的广泛关注。本项目通过模拟计算的方法，系统的研究了无基体约束的自由硼烯的本征力学和电学特性，并从原子和电子的角度分析了原子尺度褶皱导致硼烯各向异性的力学与电学性质出现的物理本质；通过施加不同种类的应变获得了外部应变对硼烯电学性能的影响规律，发现应变会使硼烯沿褶皱方向的禁带带宽明显降低；通过研究多层薄膜结构对硼烯力学及电学性质的影响发现，多层薄膜结构会使硼烯力学性质下降，并导致其电学性质各向异性消失；研究了金、银、铜、铝四种典型金属基体对硼烯结构稳定性及电学性质的影响，从能量和原子结构的角度揭示了金属基体材料对硼烯物理性质的影响规律，发现银基体-硼烯结构具有最小的界面结合能，褶皱结构最为稳定。本项目的研究可以为相关传感器设计等提供重要的理论参考，并为二维硼烯的合成制备及性能调控提供理论基础。