RELATING THE NONIDEAL DIFFRACTION FROM THE GRAPHENE LAYER STACKING PEAK TO THE ALIPHATIC CARBON ABUNDANCE IN BITUMINOUS COALS

Using conventional powder diffractometry and monochromatic Cu Kalpha X -rays, five of the Argonne Premium Coals have been examined in an atte mpt to better understand their molecular-level structuring. The diffra ctograms have been separated into contributions from mineral diffracti on, amorphous scattering, and nonideal diffraction, with the latter du e to small and nearly planar polycyclic aromatics termed graphenes. Co rrelation of the diffuse graphene layer stacking peak in each diffract ogram with the percentage of aliphatic carbon in the coal suggests tha t the aliphatic moieties in these bituminous coals cause distortions ( nonuniform strains) in the stacking of the graphene units which in tur n cause the diffuseness of this peak.