The atomic scale structure of nanographene platelets studied by X-ray diffraction, high-resolution transmission electron microscopy and molecular dynamics

• Published in: Diamond and related materials 2013-05, Vol.35, p.40-46
• Main Authors: Hawelek, L., Kolano-Burian, A., Szade, J., Maziarz, W., Woznica, N., Burian, A.
• Format: Article
• Language: English
• Subjects: Atomic structure; Computer simulation; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities in crystals; microstructure; Diffraction; Electron microscopy; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Molecular dynamics; Molecular structure; Nanographene platelets; Nanostructure; Pair correlation function; Physics; Point defects (vacancies, interstitials, color centers, etc.) and defect clusters; Specific materials; Structure and morphology; thickness; Structure of solids and liquids; crystallography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; X-ray diffraction; X-rays
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2013.03.004

The atomic structure of commercially available nanographene platelets has been studied by high energy X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and molecular dynamics simulations using the reactive empirical bond order potential. Atomic models of the structure have been constructed and then relaxed using the molecular dynamics method and the model based simulations are compared with the experimental data both in reciprocal and real space. All model relaxations and the X-ray diffraction experiments have been carried out at 300K. The proposed models consisting of about 2500 carbon atoms arranged within four graphitic layers with a diameter of 46Å, reproduced correctly all features of the experimental data. The atomic arrangement within an individual layer can be described in terms of the paracrystalline ordering, in which lattice distortions propagate proportionally to the square root of interatomic distances. The paracrystalline structure was simulated by introducing the topological point defects such as the Stone–Thrower–Wales defects, single- and double-vacancies, randomly distributed in the network. Such defects lead to curvature of individual layers and this effect was also analyzed. The generated models are related to the observations by high-resolution transmission electron microscopy. •We studied the atomic scale structure of commercially available nanographene platelets.•Structural models were constructed and their geometry optimized.•The PCF functions were compared with the X-ray diffraction experimental data.•The extended curvature mapping analyses of the optimized graphene layers were performed.•The generated models are related to the observations by HRTEM.