The nanostructure of PAN-based carbon fibers was comprehensively investigated, with an emphasis on amorphous carbon. In-situ measurement of the crystallite deformation and micromechanical analysis revealed that the amount of amorphous carbon in PAN-based carbon fibers was approximately 50%. In addition, the mechanical properties of the amorphous carbon could be obtained through the analysis, which helped to identify the structure. The weight fraction of sp² carbon layers calculated from an analytical model based on the rule-of-mixtures using Raman spectroscopy data and the crystallinity calculated by the micromechanical model indicated the differences in intermediate modulus and high modulus carbon fibers, which were affected by the measuring method. Radial distribution analysis using neutron scattering allows one to obtain a detailed structural analysis of the amorphous carbon in PAN-based carbon fibers. The analysis results suggest that the number of lattice defects in intermediate modulus carbon fibers is 20% larger than in the high modulus type and these lattice defects are present in the amorphous component. These new findings, based on extensive analysis, suggest that controlling the ratio of amorphous to crystalline carbon is one of the key factors determining the mechanical properties of PAN-based carbon fibers.

Synthesis of zeolite-templated carbons (ZTCs) was investigated by reaction molecular dynamics to explore a high-performance carbon material for CH₄ storage. We show that sixteen different types of ZTCs with a 3D network can be synthesized using different zeolite templates, and these are expected to enable the development of new carbon functional materials. Grand canonical Monte Carlo simulations using the obtained ZTCs demonstrate that the ZTCs can provide deliverable CH₄ volumetric densities larger than 180 cm³ (STP)/cm³ at 298 K (adsorption pressure: 3.4 MPa and desorption pressure: 0.1 MPa). Moreover, it is shown that, in the case of ZTC synthesized using the BEA zeolite, the deliverable CH₄ volumetric density can reach 212 cm³ (STP)/cm³ by optimizing the number of carbon atoms constituting the ZTC framework. Unfortunately, the value is far below the target of 315 cm³ (STP)/cm³ set by the U.S. Advanced Research Projects Agency and Department of Energy; however, the aforementioned data suggest that ZTCs can have a large adsorption capacity and are promising for the storage of the other energy materials.

Scanning probe microscopy (SPM) is an experimental technique that enables the investigation of surface structures and the properties of various materials with high spatial resolution. Using specially designed and prepared probe tips, it is possible to obtain images that show molecular frameworks similar to their ball-stick models. High resolution SPM is also useful to study carbon-based materials. In this article, starting from the basics of SPM, recent studies on the identification of dopants in graphene nanoribbons, the comparison of three different atomic force microscopy (AFM) techniques to observe fullerene molecules, and the correlation between AFM images and locations of metallofullerenes in peapod carbon nanotubes are explained.

The transmission electron microscope (TEM) and the scanning transmission electron microscope (STEM) are a powerful tool to understand the local structures and properties of carbon materials. The overall property of a material strongly depends on its local structures. However, the technique has not been used as efficiently as possible compared to XRD and spectroscopy. In this review, the development of spatial resolution and a method for adjusting the electron beam for high-resolution observation are briefly introduced as well as recent studies using the technique.

Neutron total scattering is a powerful tool for the structure analysis of disordered materials. The technique obtains a pair correlation function by Fourier transformation of the measured scattering cross-section from which it is possible to discuss real space atomic correlations in the disordered material. The spatial resolution depends on the highest scattering vector value and its statistical accuracy. A neutron total scattering instrument (NOVA) at the Japan Proton Accelerator Research Complex (J-PARC) realized measurements of a high resolution pair correlation function. Using this ability, the atomic structure of a zeolite-templated carbon (ZTC) framework, which shows only two clear Bragg peaks, was analyzed by comparing simulation results and suggests that the ZTC framework contains a wide range of carbon polygons such as hexagons, heptagons and octagons, while there are few pentagons.

Graphites have been widely used as electrode materials, heat resistant materials and the like, because they have high chemical stability and electrical conductivity. These superior properties can be ascribed to their highly developed and crystalline carbon structures, which can be analyzed by X-ray diffraction and transmission electron microscopy. These techniques have been regarded as primary identification tools for the crystallographic understanding of a carbon structure, but do not provide any direct information about the chemical characteristics of graphites which greatly depend on the number and quality of edge planes. The quantitative analysis of the edge planes is thus indispensable for the full understanding of carbon reactivity. However, it is not an easy task for graphites, because the total number of edge sites in these carbons is too small to be detected with high accuracy. In this paper, we introduce techniques for analyzing a small numbers of edge sites in graphites and for drawing a true picture of the carbon structure in them by estimating the average size of graphene sheets from the total numbers of carbon edge sites.