X-Ray diffraction technique: structure determination of carbonaceous materials (Review)
CHINGIZ N. BARNAKOV, GALINA P. KHOKHLOVA, ANNA N. POPOVA, SERGEY A. SOZINOV, ZINFER R. ISMAGILOV
Institute of Coal Chemistry and Material Science, Federal Research Center of Coal and Coal Chemistry, Siberian Branch, Russian Academy of Sciences, Kemerovo, Russia
Keywords: coal pitch, graphite additives, carbonization, X-ray diffraction analysis
Abstract
X-ray powder diffraction is one of the most potential characterization tools and a nondestructive technique for characterizing carbon based materials and their composite properties. The method is used to measure phase identification, quantitative analysis and to determine structure imperfections of samples. The paper summarizes results of investigations of carbonaceous materials structure. X-ray diffraction is used as the technique for characterizing the structural order. As it turned out the carbonaceous materials obtained by the low-temperature graphitization of coal-tar pitch contain contemporaneously several phases of crystalline carbon and amorphous carbon with turbostratic structure. In the present report, to explain the heterogeneous structure of carbonaceous materials we compare data of X-ray diffraction analysis for the (00l) reflection from the main crystal face. It was found that the (002) and (004) reflections are the superpositions of components, which correspond to the structural phases of crystalline carbon and amorphous carbon with different interplanar spacing. The ratio between the integrated intensities of separated reflection components accounts for the ratio between these phases; along with interplanar spacing, this ratio characterizes carbonaceous materials and makes it possible to detect difference between them. The degree of ordering, the interlayer spacing ( d 002), and the crystalline sizes ( L a and L c) are considered the key parameters for evaluating the stacking structure of carbonaceous materials.
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