Li Xiaowen, Zhang Fusheng, Li Jian, Wang Zeping, Huang Zhengyong, Yu Jiabing, Zheng Kai, Chen Xianping
College of Optoelectronic Engineering and Key Laboratory of Optoelectronic Technology & Systems Education Ministry of China, Chongqing University, 400044 Chongqing, China.
School of Electrical Engineering and State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, 400044 Chongqing, China.
J Phys Chem Lett. 2023 Mar 16;14(10):2692-2701. doi: 10.1021/acs.jpclett.3c00058. Epub 2023 Mar 9.
Two-dimensional (2D) materials composed of pentagon and Janus motifs usually exhibit unique mechanical and electronic properties. In this work, a class of ternary carbon-based 2D materials, CXY ( = 2, 3; = 1, 2; X, Y = B, N, Al, Si, P), are systematically studied by first-principles calculations. Six of 21 Janus penta-CXY monolayers are dynamically and thermally stable. The Janus penta-CBAl and Janus penta-SiCN exhibit auxeticity. More strikingly, Janus penta-SiCN exhibits an omnidirectional negative Poisson ratio (NPR) with values ranging from -0.13 to -0.15; in other words, it is auxetic under stretch in any direction. The calculations of piezoelectricity reveal that the out-of-plane piezoelectric strain coefficient () of Janus panta-CBAl is up to 0.63 pm/V and increases to 1 pm/V after a strain engineering. These omnidirectional NPR, giant piezoelectric coefficients endow the Janus pentagonal ternary carbon-based monolayers as potential candidates in the future nanoelectronics, especially in the electromechanical devices.
由五边形和Janus结构单元组成的二维（2D）材料通常表现出独特的机械和电子性能。在这项工作中，通过第一性原理计算系统地研究了一类三元碳基二维材料CXY（=2,3；=1,2；X,Y = B、N、Al、Si、P）。21种Janus五边形CXY单层中有6种是动态和热稳定的。Janus五边形CBAl和Janus五边形SiCN表现出负泊松比特性。更引人注目的是，Janus五边形SiCN表现出全方位的负泊松比（NPR），其值范围为-0.13至-0.15；换句话说，它在任何方向拉伸时都具有负泊松比特性。压电性计算表明，Janus五边形CBAl的面外压电应变系数（）高达0.63 pm/V，经过应变工程处理后增加到1 pm/V。这些全方位的NPR、巨大的压电系数使Janus五边形三元碳基单层成为未来纳米电子学中的潜在候选材料，特别是在机电设备中。
