Structural studies of activated carbons by pulsed neutron diffraction

Pulsed neutron diffraction results are presented for a series of activated carbons with a variable microporosity. The results cover a wide Q-range extending up to 50 Angstrom(-1) and enable the pair correlation function to be evaluated with good spatial resolution. The diffraction pattern shows a broad oscillatory behaviour representative of a highly defective crystal structure and differs considerably from graphite. Detailed investigation shows that the local atomic structure is similar to that of graphite and exhibits the expected hexagonal network but that the first peak arising from the carbon-carbon bond has two components, indicating a quinoidal distortion of the network. The correlation length within the graphene sheet is short ranged and the inter-layer spacing also displays some disorder with an increased spacing compared with graphite. The data provide a good basis for the detailed modelling of the structure and exhibit characteristics that could not have been easily observed by other techniques.