Abstract
Structural studies by means of neutron diffraction of activated carbons,prepared from a polymer of phenol formaldehyde resin by carbonization and activation processes, with variable porosity, arepresented. The neutron scattering data were recorded over the rangeof the scattering vector Q from 2.5 to 500 nm-1. Thestructure of activated carbons has been described in terms ofdisordered graphite-like layers with very weak interlayercorrelations. The model has been generated by computer simulationsand its validity has been tested by comparison of the experimentaland calculated intensity functions. Modelling studies have shownthat the model containing 3-4 layers each about 2 nm in diameteraccounts for the experimental data and that graphite layers arerandomly translated and rotated, according to the turbostraticstructure. Near-neighbour carbon-carbon distances of about0.139 nm and 0.154 nm have been determined. The Debye-Waller factorexp (-Q2σ2/2) with σ = σ0(r)1/2 suggestsa paracrystalline structure within a single layer. The value ofthe interlayer spacing of 0.36 nm has been found from paracrystalline simulations of the layer arrangement in the c-axisdirection. The high quality of the experimental data has enableddetermination of the coordination numbers, the interatomic distancesand their standard deviations using a curve-fitting procedure overthe Q-range from 250 nm to 500 nm, providing structuralinformation about short- and intermediate-range ordering.
Published Version
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