Abstract:
The estimation of the active surface area (ASA) of various macrocrystalline graphitic materials
is industrially valuable but the microstructures of these materials are still contestable.
This in turn has led to difficulties in the unambiguous interpretation of crystallographic
measurements with powder X-ray diffraction (pXRD) and Raman spectroscopy as well as
their relationship to the ASA. To resolve this issue a systematic approach is required. As
a starting point two widely accepted pXRD and Raman methodologies were utilized. Purified,
oxidized, natural graphite flakes were extensively examined to elucidate the essential
microstructural features. Based on this an illustrative model was formulated as grounds for
interpreting the measured crystallite domain sizes. Only one of the crystallographic parameters
could be linked to the observed microstructure. For macrocrystalline graphite both
techniques are subject to instrumental limitations and should not be used. Due to the
non-linearity of the correlations they are prone to measurement uncertainty and should
not be used above acceptable limits. In addition, the current inability to distinguish
between different defect types leads to ambiguous results. Despite being a single, interrelated
crystal the composite nature of the flakes will make it difficult to relate even an ideal,
accurate domain size measurement to the ASA.
