Direct observation of raw coals in lattice fringe mode using high-resolution transmission electron microscopy

High-resolution transmission electron microscopy (HRTEM) technique has been used to characterize several coals. By careful examination, direct evidence of layered structure in a wide range of coals was for the first time obtained from HRTEM lattice fringes. In general, most of the layers in all coals occur singly or in stacks of 4-5 layers. Quantitative analysis of coal images showed that average number of layers per stack and layer size remain almost the same for lignite and high volatile bituminous and medium volatile bituminous coals, and they are larger for low volatile bituminous coal and anthracite.