de Oliveira Raphaela, Barbosa Yoshida Ana B, Rabahi Cesar R, O Freitas Raul, Teixeira Verônica C, de Matos Christiano J S, Galvão Gobato Yara, Barcelos Ingrid D, Cadore Alisson R
Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970 Campinas, SP, Brazil.
Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-100 Campinas, SP, Brazil.
Nanotechnology. 2024 Oct 1;35(50). doi: 10.1088/1361-6528/ad7b3a.
Biotite, an iron-rich mineral belonging to the trioctahedral mica group, is a naturally abundant layered material (LM) exhibiting attractive electronic properties for application in nanodevices. Biotite stands out as a non-degradable LM under ambient conditions, featuring high-quality basal cleavage-a significant advantage for van der Waals heterostructure (vdWH) applications. In this work, we present the micro-mechanical exfoliation of biotite down to monolayers (1Ls), yielding ultrathin flakes with large areas and atomically flat surfaces. To identify and characterize the mineral, we conducted a multi-elemental analysis of biotite using energy-dispersive spectroscopy mapping. Additionally, synchrotron x-ray fluorescence and infrared nano-spectroscopy were employed to probe its iron content and vibrational signature in few-layer form, respectively, with sensitivity to the layer number. We have also observed good morphological and structural stability in time (up to 12 months) and no important changes in their physical properties after thermal annealing processes in ultrathin biotite flakes. Conductive atomic force microscopy evaluated its electrical capacity, revealing an electrical breakdown strength of approximately 1 V nm. Finally, we explore the use of biotite as a substrate and encapsulating LM in vdWH applications. We have performed optical and magneto-optical measurements at low temperatures. We find that ultrathin biotite flakes work as a good substrate for 1L-MoSe, comparable to hexagonal boron nitride flakes, but it induces a small change of the 1L-MoSe-factor values, most likely due to natural impurities on its crystal structure. Furthermore, our results show that biotite flakes are useful systems to protect sensitive LMs such as black phosphorus from degradation for up to 60 days in ambient air. Our study introduces biotite as a promising, cost-effective LM for the advancement of future ultrathin nanotechnologies.
黑云母是一种富含铁的矿物，属于三八面体云母族，是一种天然丰富的层状材料（LM），具有吸引人的电子特性，可应用于纳米器件。在环境条件下，黑云母作为一种不可降解的层状材料脱颖而出，具有高质量的底面解理性——这是范德华异质结构（vdWH）应用的一个显著优势。在这项工作中，我们展示了将黑云母微机械剥离至单层（1L），得到了大面积且原子级平整表面的超薄薄片。为了识别和表征该矿物，我们使用能量色散光谱映射对黑云母进行了多元素分析。此外，同步加速器X射线荧光和红外纳米光谱分别用于探测其以少层形式存在时的铁含量和振动特征，对层数具有敏感性。我们还观察到超薄黑云母薄片在长达12个月的时间内具有良好的形态和结构稳定性，并且在热退火处理后其物理性质没有重要变化。导电原子力显微镜评估了其电容，揭示出约1 V nm的电击穿强度。最后，我们探索了黑云母在vdWH应用中作为衬底和封装层状材料的用途。我们在低温下进行了光学和磁光测量。我们发现超薄黑云母薄片作为1L-MoSe的良好衬底，与六方氮化硼薄片相当，但它会引起1L-MoSe因子值的微小变化，最有可能是由于其晶体结构上的天然杂质。此外，我们的结果表明，黑云母薄片是有用的系统，可在环境空气中保护诸如黑磷等敏感层状材料长达60天不发生降解。我们的研究将黑云母引入为一种有前途、具有成本效益的层状材料，以推动未来超薄纳米技术的发展。
