Microstructure of pyrocarbons from pair distribution function analysis using neutron diffraction

We present a microstructural investigation of two different pyrocarbons (PyCs), belonging respectively to the rough laminar (RL) and smooth laminar (SL) families. The structure of the materials is analyzed in terms of their pair distribution functions (PDFs) as determined from neutron diffraction experiments. The data are correlated with polarized light optical microscopy, high resolution transmission electron microscopy, Raman microspectrometry, X-ray diffraction, He pycnometry, elastic recoil detection analysis and secondary ion mass spectrometry. Results show that the two materials may be clearly distinguished using the PDF data above a 15 Å distance. The PDF of the more ordered carbon (the RL PyC) is also compared to data obtained from an image-guided atomistic reconstruction, showing excellent agreement.