Absorption and diffusion of beryllium in graphite, beryllium carbide formation investigated by density functional theory

The formation of beryllium carbide from beryllium and graphite is here investigated. Using simple models and density functional theory calculations, a mechanism leading to beryllium carbide is proposed; it would be (i) first diffusion of beryllium in graphite, (ii) formation of a metastable beryllium-intercalated graphitic compound, and (iii) phase transition to beryllium carbide. The growth of beryllium carbide is further controlled by defects' formations and diffusion of beryllium through beryllium carbide. Rate limiting steps are the formation of defects in beryllium carbide, with estimated activation energies close to 2 eV.