Ma Fengxian, Jiao Yalong, Wu Weikang, Liu Ying, Yang Shengyuan A, Heine Thomas
College of Physics, Hebei Key Laboratory of Photophysics Research and Application, Hebei Normal University, 050024 Shijiazhuang, China.
Faculty for Chemistry and Food Chemistry, TU Dresden, Bergstraße 66c, 01069 Dresden, Germany.
Nano Lett. 2021 Mar 24;21(6):2356-2362. doi: 10.1021/acs.nanolett.0c04154. Epub 2021 Mar 3.
Upon strain, most materials shrink normal to the direction of applied strain. Similarly, if a material is compressed, it will expand in the direction orthogonal to the pressure. Few materials, those of negative Poisson ratio, show the opposite behavior. Here, we show an unprecedented feature, a material that expands normal to the direction of stress, regardless if it is strained or compressed. Such behavior, namely, half-auxeticity, is demonstrated for a borophene sheet stabilized by decorating Pd atoms. We explore Pd-decorated borophene, identify three stable phases of which one has this peculiar property of half auxeticity. After carefully analyzing stability and mechanical and electronic properties we explore the origin of this very uncommon behavior and identify it as a structural feature that may also be employed to design further 2D nanomaterials.
在应变时，大多数材料会在垂直于施加应变的方向上收缩。同样，如果材料受到压缩，它会在与压力正交的方向上膨胀。很少有材料，即负泊松比的材料，表现出相反的行为。在这里，我们展示了一个前所未有的特性，一种材料无论受拉还是受压，都会在垂直于应力的方向上膨胀。这种行为，即半负泊松比，在通过装饰钯原子而稳定的硼烯薄片中得到了证明。我们研究了装饰钯的硼烯，确定了三个稳定相，其中一个具有这种半负泊松比的特殊性质。在仔细分析了稳定性以及力学和电子性质之后，我们探究了这种非常罕见行为的起源，并将其确定为一种结构特征，该特征也可用于设计进一步的二维纳米材料。
