Gao Wei, Zhao Yan, Yin Hong
State Key Lab of Superhard Materials, Jilin University Qianjin Street 2699 Changchun 130012 PR China
RSC Adv. 2018 Feb 5;8(11):5976-5983. doi: 10.1039/c7ra12872j. eCollection 2018 Feb 2.
Hexagonal boron nitride (h-BN) is of great importance in imaging, thermal and quantum applications in the mid-infrared regions (most of which are size related) for its natural hyperbolic properties. Liquid exfoliation is a promising production approach, however it is limited by the wide range of nanosheet length and thickness. Here we demonstrate a simple and effective method to sort the exfoliated nanosheets according to their lateral sizes. The process uses a combination of low-rate and high-rate configurations to separate the lateral lengths ranging from 1 to 3 μm. In contrast to Raman spectroscopy, infrared results exhibit intensive dependence on the nanosheet length, where the E phonon frequency and intensity ratio of E to A modes are significantly sensitive to the nanosheet length owing to the large anisotropy between the in-plane and out-of-plane axes.
六方氮化硼（h-BN）因其天然的双曲线特性，在中红外区域的成像、热学和量子应用（其中大部分与尺寸相关）中具有重要意义。液体剥离是一种很有前景的制备方法，然而它受到纳米片长度和厚度范围广泛的限制。在这里，我们展示了一种简单有效的方法，可根据横向尺寸对剥离的纳米片进行分类。该过程使用低速和高速配置的组合来分离横向长度在1至3μm之间的纳米片。与拉曼光谱不同，红外结果显示出对纳米片长度的强烈依赖性，由于面内和面外轴之间存在较大的各向异性，E声子频率以及E与A模式的强度比对于纳米片长度非常敏感。
