Quantitative Correlation Between Raman D′ Band Characteristics and Texture Fragmentation in Thermally Oxidized Graphite Using a Boundary Intersection Descriptor

Establishing a direct and quantitative link between microstructural features and spectroscopic signatures remains a key challenge in the characterization of graphitic materials. In this work, thermally oxidized high‐purity graphite is used as a model system to investigate the relationship between Raman spectral features and microstructural fragmentation revealed by field‐emission scanning electron microscopy (FESEM). Controlled oxidative thermal treatment in air was applied to induce structural disorder while preserving the overall graphitic phase, as confirmed by X‐ray diffraction (XRD). A line‐intercept–based boundary intersection descriptor (BID) was introduced to quantify microstructural fragmentation from FESEM images in a consistent and reproducible manner. Raman spectroscopy revealed a progressive evolution of the defect‐related D' band with increasing treatment severity. Among the investigated Raman metrics, the full width at half maximum (FWHM) of the D' band exhibited a strong and systematic correlation with BID, whereas intensity‐ and area‐based ratios showed a weaker and less consistent dependence on microstructural fragmentation. The combined analysis demonstrates that D'‐band linewidth broadening provides a sensitive and physically meaningful spectroscopic probe of in‐plane disorder associated with flake fragmentation and boundary density. This study highlights the advantage of linewidth‐based Raman descriptors over conventional intensity metrics and establishes a framework for correlating Raman spectroscopy with electron microscopy in graphitic and other layered materials.