煤系石墨微晶结构各向异性和非均质性的拉曼光谱表征  

Anisotropic and Heterogeneity of Coal Measures Graphite Micro-Crystalline Structure by Raman Spectroscopy

作　　者：李焕同[1,2] 邹晓艳 夏炎 张卫国 LI Huan-tong;ZOU Xiao-yan;XIA Yan;ZHANG Wei-guo(College of Geology and Environment,Xi'an University of Science and Technology,Xi'an 710054,China;Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences),Ministry of Education,Wuhan 430074,China;College of Urban,Rural Planning and Architectural Engineering,Shangluo University,Shangluo 726000,China;Coal Geology Survey of Ningxia Hui Autonomous Region,Yinchuan 750011,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054 [2]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [3]商洛学院城乡规划与建筑工程学院,陕西商洛726000 [4]宁夏回族自治区煤炭地质局,宁夏银川750011

出　　处：《光谱学与光谱分析》2024年第12期3560-3567,共8页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(41502160);宁夏回族自治区重点研发计划项目(2021BEG02015);西安科技大学优秀青年科技基金项目(2019YQ2-08);商洛学院科研基金项目(23SKY002)资助。

摘　　要：煤对温度和压力等地质环境条件十分敏感,在构造应力驱动下煤中“石墨微晶”结构取向生长,物理化学和结构呈现各向异性。采用X射线衍射和拉曼光谱对不同石墨化程度样品进行表征,结果表明:在高温主导,剪应力作用参与下,煤层顺层滑动,构造变形使石墨微晶旋转、择优取向,随着沿C轴方向堆砌高度的增加。以堆砌度Lc≤5 nm划分为无烟煤阶段,为碳层随机定向或无规则排列的紊层结构,光学各向同性;以Lc≥30 nm时视为较完善石墨结构形成的标志,光学各向异性显著;在10~20 nm间属于石墨化结构不够完善的过渡态结构(半石墨阶段)。石墨阶段样品SXL100、SXL130层理面、边缘面和粉末的拉曼光谱中1350 cm^(-1)带(D_(1))、1620 cm^(-1)带(D_(2))都较明显,但是石墨边缘面拉曼光谱中D1峰半高宽、D_(1)与G峰强度比(I_(D1)/IG,R_(1))、D_(2)峰与G峰强度比(I_(D2)/IG,R_(3))显著高于层理面,显示强度比等拉曼参数依赖于煤系石墨边缘面的取向。D1峰强度依赖样品缺陷或无序程度,边缘面D_(2)峰具有非对称特征,双峰结构显著,并且D′1峰随D_(2)峰变化,亦显示边缘面缺陷的光谱行为。用煤系石墨缺陷密度或有序度表征指标R_(1)划分无烟煤(R_(1)≥1.0)、半石墨(1.0>R_(1)≥0.5)和石墨(R_(1)<0.5)等阶段,并评价煤系石墨均匀程度及不同石墨化程度组分的比例及分布,发现变质无烟煤CM130N样中超前演化达到半石墨结构占比达3.52%,半石墨BC210样中无烟煤结构占比46.40%,SXL130样整体石墨化,但其中无烟煤结构占比仍有3.84%,层理面和边缘面结构中仍存在缺陷,建立的方法在区分无烟煤、半石墨更具优势。在拉曼激光入射方向一定时,可利用R_(1)、R_(3)参数来探讨受构造应力影响的煤系石墨层理面拉曼光谱特征,分别评价了石墨化不均一性和石墨微晶取向。Coal is very sensitive to geological environmental conditions such as temperature and pressure.Driven by tectonic stress,coal's“graphite crystallite”structure grows in orientation,and the physical chemistry and structure show anisotropy.X-ray diffraction and Raman spectroscopy characterized the samples with different degrees of graphitization.The results show that the coal seam slides along the layer under high temperatures and shear stress.The structural deformation makes the graphite crystallites rotate and preferentially oriented,increasing the stacking height along the c-axis direction.The anthracite stage is divided by the stacking degree Lc≤5 nm,which is a turbulent layer structure with random orientation or irregular arrangement of carbon layers,optically isotropic;when Lc≥30 nm,it is regarded as a sign of the formation of a perfect graphite structure,and the optical anisotropy is significant.It belongs to the transition state structure(semi-graphite stage)with an imperfect graphitization structure between 10~20 nm.The 1350 cm^(-1) band(D1)and 1620 cm^(-1) band(D_(2))in the Raman spectra of SXL100 and SXL130 samples in the graphite stage are obvious.Still,the full width at half maximum of the D_(1) to G peak(I_(D1)/IG,R_(1)),and the intensity ratio of D_(2) to G peak(I_(D2)/IG,R_(3))in the Raman spectra of the graphite edge plane are significantly higher than those of the preferred orientation plane,indicating that the Raman parameters such as intensity ratio depend on the orientation of the edge plane of coal-based graphite.The intensity of the D_(1) peak depends on the degree of defect or disorder of the sample.The D_(2) peak of the edge plane has asymmetric characteristics,and the bimodal structure is significant.The D′1 peak changes with the D_(2) peak,which also shows the spectral behavior of the edge plane defect.The stages of anthracite(R_(1)≥1.0),semi-graphite(1.0>R_(1)≥0.5),and graphite(R_(1)<0.5)were divided by the defect density or order degree index R_(1) of coal measures graphite

关 键 词：煤系石墨 各向异性 非均质性 拉曼光谱 微晶结构 

分 类 号：TQ533.6[化学工程—煤化学工程]