Mechanistic elucidation of vacancy-induced polarization transfer in graphite

A comprehensive understanding of vacancy-induced strengthening and polarization mechanisms is essential for enhancing the mechanical and electrical performance of nuclear graphite, wherein the vacancy-governed bond contraction and polarization-transfer mechanism may provide a possible theoretical framework for elucidating irradiation-induced defect formation and property modulation. This study investigated the intrinsic nature of vacancy-induced dipole superposition, polarization transfer, and their coupled electromechanical effects in an undercoordinated graphite system. It identified a dual mechanism involving bond contraction and dipole polarization in this system. Results show that a single vacancy enhances the mechanical strength of graphite within the microstrain regime (<0.8%), with C–C bonds between undercoordinated carbon atoms contracting by ∼2.4%. Charge redistribution generates ring-like distributions of energy and electron density around vacancies. Fermi peak emerge at the Fermi level, with the α- and β-vacancy polarization transfer quantified: polarization peak intensities reach ∼0.45% higher at α1 than at α 3 . Hydrogen adsorption at β vacancies is strongly exothermic, with calculated adsorption energies of −3.64 eV and H–C bond lengths of ∼1.513 Å. These findings provide a quantitative basis for understanding irradiation-induced defect formation and property modulation in nuclear graphite. • Vacancy-edge dipoles induce an anomalous Fermi level. • Vacancy-driven bond contraction yields local strengthening. • Hydrogen incorporation splits bands at the Fermi level.