We use molecular dynamics simulations (MD) to study piezoelectric properties of hexagonal boron nitride nanosheets (BNNS) and reveal how piezoelectric properties depend on size and shape. We first analyze how the macroscopic shape affects the full 2D structure symmetry and its piezoelectric tensor. In particular, we demonstrate that a hexagonal (rectangular)-shaped BNNS belongs to the hexagonal m2 (monoclinic m) point group. Our simulation results show that the piezoelectric constants of BNNS depend strongly on the macroscopic shape, in agreement with the symmetry of the structure, but are nearly independent of the macroscopic size. The present study provides a detailed understanding of the piezoelectric properties of finite size BNNS and guidance to future experiments and optimization of 2D piezoelectric materials in general.

中文翻译：

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单层六方氮化硼纳米片的形状和尺寸依赖性压电特性

我们使用分子动力学模拟 (MD) 来研究六方氮化硼纳米片 (BNNS) 的压电特性，并揭示压电特性如何依赖于尺寸和形状。我们首先分析宏观形状如何影响完整的二维结构对称性及其压电张量。特别是，我们证明了一个六边形（矩形）形状的 BNNS 属于六边形m 2（单斜m) 点群。我们的模拟结果表明，BNNS 的压电常数强烈依赖于宏观形状，与结构的对称性一致，但几乎与宏观尺寸无关。本研究提供了对有限尺寸 BNNS 压电特性的详细了解，并为未来的实验和一般二维压电材料的优化提供了指导。