不同变质程度煤系石墨结构特征

Structure Characteristics of Different Metamorphic Grade Coal-Based Graphites

煤系石墨形成于煤层的接触变质带,通常被当作煤开采利用而造成严重的资源浪费.为了了解煤系石墨在成矿过程中分子结构的变化,利用X射线衍射(XRD)、透射电子显微镜(TEM)、拉曼光谱(Raman)等技术,对我国陕西凤县、湖南新化和湖南郴州鲁塘地区处于不同变质程度煤系石墨进行测试分析.结果表明:凤县样品石墨化度最低,仍处于超无烟煤阶段;新化石墨处于半石墨阶段,鲁塘样品石墨化程度最高,其结构比较完美,接近于三维有序理想石墨结构,但仍存在少量的无序化畴.XRD分析显示随着样品石墨化程度的升高,堆砌层数与堆砌延展度均增大;拉曼光谱中D峰减弱,G峰逐渐增强并尖锐,D峰与G峰的强度比和面积比均减小,显示碳原子sp2平面域增大.透射电子显微镜晶格像显示,由无烟煤向石墨结构转变过程中,煤的芳香片层首先形成类石墨结构的微柱体,然后这些微柱体之间相互联结,最后形成横向无限延展的石墨晶层.

To reveal the change of C atom lattice arrangements in coal-based graphite,samples with different metamorphic grades from several areas,such as Shaanxi Fengxian,Hunan Xinhua and Hunan Lutang,were characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）and Raman spectrum（Raman）.The results show that the metamorphism degree of Fengxian graphite is in the stage of super anthracite,and that of Xinhua is semi-graphite.The graphitization degree of samples from Lutang is the highest,and its structure is close to the three dimensions ordered ideal graphite,but a little of disordered domain still exists in the structure of Lutang graphite.XRD shows that the distance between C atom layers decreases with graphitization degree increasing,but the numbers of layers and the area of single layers increase.The G peak in the Raman spectrum is gradually stronger and sharper while the D peak is weaker,and the intensity ratio and area ratio of D peak and G peak are all reduced with the graphitization increasing,which demonstrates the increasing sp2 planar area.The lattice images of TEM show that the graphite-like pillars were formed at first in the graphitization,and then these pillars were united laterally with each other to form the graphite lattice structure.