Rhombohedral stacking-faults in exfoliated highly oriented pyrolytic graphite

作者：Filippo S. Boi, Cheng-Yang Lee, Shanling Wang, Hansong Wu, Li Lei, Zhang Lin, Jiaxin Song, Yixin Dai, Ayoub Taallah, Omololu Odunmbaku, Anna Corrias, A. Baron-Wiecheć, Shuping Zheng, Salvatore Grasso · 发表于：Carbon Trends · 年份：2024 · DOI：10.1016/j.cartre.2024.100345 · 被引用次数：13 · 研究领域：Graphene research and applications、Graphite, nuclear technology, radiation studies、Fiber-reinforced polymer composites

The recent observation of possible granular superconductivity in highly oriented pyrolytic graphite (HOPG) has attracted significant research interest. Here we report a novel investigation on the structural-properties of exfoliated-HOPG. We investigated two types of exfoliation methods, involving either a full (method-1) or partial (method-2) contact between adhesive tape and the main HOPG. Structural characterization was obtained by employing X-ray diffraction (XRD), Raman spectroscopy and electron microscopy (SEM). In particular, Raman point and mapping spectroscopy revealed significant structural-transitions from ABA (Bernal) to ABC (rhombohedral) stacking (stacking-faults), in those samples obtained with the method-2. Interestingly, strained regions exhibiting structural-deformations with a ridge-like morphology were reproducibly identified. The acquired Raman-spectra revealed a local enhancement of the D and D’ bands-intensity together with contributions arising from Electronic Raman Scattering (ERS) across the band-gap of rhombohedral-graphite, at middle (∼1870 cm−1) and high (∼ 2680 cm−1) frequency. HRTEM of the samples produced with the method-2 allowed also for the identification of local-coexistence of ripplocation-like defects with moiré superlattices, an indicator of non-uniform c-axis configuration.