Comparative XRD, Raman, and TEM Study on Graphitization of PBO-Derived Carbon Fibers

Abstract

Carbon fibers, obtained by carbonizing poly(p-phenylene benzobisoxazole) (PBO) fibers at 900 °C, graphitize extensively upon heat treatment at higher temperatures (2700 °C). In this work, XRD, Raman spectroscopy, and HRTEM are used to monitor the structural and nanostructural transformations of the carbon material under heat-treatment at several temperatures in the interval 900–2800 °C. These different techniques provide complementary information, especially regarding the spatial resolution they achieve. They highlight a specific nonconventional mode of graphitization for this unexpectedly graphitizable precursor. The reliability in the determination of L a crystallite sizes from these three techniques is compared and discussed. The existence of four steps in the graphitization of PBO-derived carbon fibers is inferred.

Tuning the grade of graphene: Gamma ray irradiation of free-standing graphene oxide films in gaseous phase

“…In addition, the full width at half maximum of the (2 0 0) peak was found to remain statistically unchanged upon irradiation suggesting no change to the d-spacing and thus to the crystalline matrix unit dimension. This trend was also confirmed with Raman analysis, which was used to characterize the vibrational modes of surface functional groups, indications of change across the graphitic carbon lattice [47,48]. Two remarkable peaks at 1355 and 1599 cm −1 are visible on the Raman spectra in Fig.…”

New Mechanistic Insights on Na-Ion Storage in Nongraphitizable Carbon

“…The scale discrepancy between the XRD and Raman L a values has been noted before, as Raman measurements tend to overestimate the L a values. 26 However, when performing a linear regression of the Raman L a values vs the XRD L a values, we find an R 2 of 0.95, thus confirming the increasing trend in L a in the carbon materials ( Figure S7). Additional information from the Raman data includes an I D /I G ratio, which can be used to quantify the concentration of defects along the graphene sheets.…”

Microstructure and photocatalytic activity of electrospun carbon nanofibers decorated by TiO 2 nanoparticles from hydrothermal reaction/blended spinning

“…The structure parameters of carbon fibers including the interlayer distance d 002 , which was calculated by XRD spectra using Bragg equations [37], were shown in Table 2. In addition, carbon fiber has obvious diffraction peak at about 25.6 °, which is characteristic of carbon fiber (002) crystal plane diffraction peak [38]. It was evident that the diffraction peak of anatase TiO 2 (101) and carbon fiber (002) was coincident.…”