Effect of temperature on the graphitization process of a semianthracite

In this work, a Spanish semianthracite was graphitized at temperatures greater than or equal to 2400 degreesC. The aim of this research was to study the influence of the temperature on the evolution of the structural order of the graphitic materials obtained. Crystalline parameters such as interlayer spacing, d(002), and domain sizes L-c and L-a were calculated from X-ray diffraction (XRD) measurements. The intensity ratio of the D and G Raman bands was used to assess the degree of orientation of these materials. Analysis of the XRD and Raman data of the graphitized samples allowed one to conclude that their structural order tend to increase with the temperature of treatment. Interlayer distances d(002) remained almost unchanged in the whole range of temperatures studied. It seems that after a given value of this parameter is reached, improvement of samples' crystallinity is only related to crystallite-size growth. According to the Raman I-D/I-D + I-G ratio, an increase of the bidimensional structural order with the graphitization temperature is observed. The degree of graphitization achieved at the highest temperature employed can be improved by increasing the time of treatment. (C) 2002 Elsevier Science B.V All rights reserved.