CAS Key Laboratory of Materials for Energy Conversion and Department of Material Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
ACS Nano. 2012 May 22;6(5):4104-12. doi: 10.1021/nn300495t. Epub 2012 Apr 13.
We perform a comprehensive study of the effects of line defects on electronic and magnetic properties of monolayer boron-nitride (BN) sheets, nanoribbons, and single-walled BN nanotubes using first-principles calculations and Born-Oppenheimer quantum molecular dynamic simulation. Although line defects divide the BN sheet (or nanotube) into domains, we show that certain line defects can lead to tailor-made edges on BN sheets (or imperfect nanotube) that can significantly reduce the band gap of the BN sheet or nanotube. In particular, we find that the line-defect-embedded zigzag BN nanoribbons (LD-zBNNRs) with chemically homogeneous edges such as B- or N-terminated edges can be realized by introducing a B(2), N(2), or C(2) pentagon-octagon-pentagon (5-8-5) line defect or through the creation of the antisite line defect. The LD-zBNNRs with only B-terminated edges are predicted to be antiferromagnetic semiconductors at the ground state, whereas the LD-zBNNRs with only N-terminated edges are metallic with degenerated antiferromagnetic and ferromagnetic states. In addition, we find that the hydrogen-passivated LD-zBNNRs as well as line-defect-embedded BN sheets (and nanotubes) are nonmagnetic semiconductors with markedly reduced band gap. The band gap reduction is attributed to the line-defect-induced impurity states. Potential applications of line-defect-embedded BN nanomaterials include nanoelectronic and spintronic devices.
我们使用第一性原理计算和 Born-Oppenheimer 量子分子动力学模拟，对单层氮化硼（BN）片、纳米带和单壁 BN 纳米管中线缺陷对电子和磁性质的影响进行了全面研究。尽管线缺陷将 BN 片（或纳米管）分割成畴，但我们表明，某些线缺陷可以在 BN 片（或不完美的纳米管）上形成定制的边缘，从而显著降低 BN 片或纳米管的带隙。特别是，我们发现，通过引入 B(2)、N(2)或 C(2)五元环-八元环-五元环（5-8-5）线缺陷或通过形成反位线缺陷，可以实现具有化学均匀边缘（如 B 或 N 端）的嵌入式锯齿状 BN 纳米带（LD-zBNNRs）。预测仅具有 B 端的 LD-zBNNRs 在基态下为反铁磁半导体，而仅具有 N 端的 LD-zBNNRs 为金属且具有简并的反铁磁和铁磁态。此外，我们发现，氢化 LD-zBNNRs 以及嵌入式线缺陷的 BN 片（和纳米管）是无磁性半导体，带隙明显减小。带隙减小归因于线缺陷诱导的杂质态。嵌入式线缺陷 BN 纳米材料的潜在应用包括纳米电子学和自旋电子学器件。
