Structure analysis of graphite fluoride by the Rietveld method

Abstract

The structure of the graphite fluoride prepared from mesocarbon microbeads (MCMBs) was analyzed by the Rietveld method based on the two types of space groups proposed previously (P 6m2 − and P 3m1). The weighted pattern R-factor of the latter (25.28) was smaller than that of the former indicating that P 3m1 is more valid. However, the result of the X-ray diffraction pattern of (CF) n prepared from the flaky natural graphite revealed that the space group of (CF) n is P 6m2 −. This inconsistency could be explained by the analysis of the turbostratic nature of the pristine carbon. The projected probability function of MCMBs showed a rotational misorientation of 0.6 ° which generated the moiré pattern between the adjacent carbon layer planes. The misorientation produced two types of stacking sequences along the c-axis, AB and AA in a crystallite of pristine carbon, and the graphite fluoride prepared from such a turbostratic carbon has the AA′- and AB′-stacking structures in a crystallite. As a result, the space group of the graphite fluoride is apparently close to P 3m1 and the 001 reflection in the case of P 6m2 − disappears or is weakened.