Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu, Shandong Province, 273165, China.
Center for High Pressure Science and Technology Advanced Research, Beijing, 100094, China.
Phys Chem Chem Phys. 2023 Jun 7;25(22):15400-15406. doi: 10.1039/d3cp00692a.
Elemental boron has evoked substantial interest owing to its chemical complexity in nature. It can form multicenter bonds due to its electron deficiency, which induces the formation of various stable and metastable allotropes. The search for allotropes is attractive for finding functional materials with fascinating properties. Using first-principles calculations with evolutionary structure search, we have explored boron-rich K-B binary compounds under pressure. A series of dynamically stable structures (2 KB, KB, KB, and KB) containing boron framework with open channels are predicted, which can possibly be synthesized under high pressure and high temperature conditions. After the removal of K atoms, we obtain four novel boron allotropes, -B, -B, -B, and -B, which exhibit dynamical, thermal, and mechanical stability at ambient pressure. Among them, -B contains an unusual B pentagonal bipyramid and appears in a bonding combination of seven-center-two-electron (7c-2e) B-B π bonds, which is the first time to be identified in three-dimensional boron allotropes. Interestingly, our calculation reveals that -B can act as a superconductor with a value of 29.1 K under ambient conditions.
由于硼在自然界中的化学复杂性，元素硼引起了人们的极大兴趣。由于其电子缺乏，硼可以形成多中心键，从而诱导各种稳定和亚稳定同素异形体的形成。寻找同素异形体对于寻找具有迷人性质的功能材料具有吸引力。我们使用基于第一性原理的计算和进化结构搜索，在压力下探索了富硼 K-B 二元化合物。预测了一系列含有开放通道的硼骨架的动力学稳定结构（2KB、KB、KB 和 KB），它们可能在高压高温条件下合成。在去除 K 原子后，我们得到了四种新的硼同素异形体-B、-B、-B 和 -B，它们在常压下表现出动力学、热学和力学稳定性。其中，-B 含有一个不寻常的五边形双锥硼，出现在七个中心两个电子（7c-2e）B-Bπ键的键合组合中，这是在三维硼同素异形体中首次被识别。有趣的是，我们的计算表明，-B 在常压下可以作为超导材料，超导转变温度为 29.1K。
