Self-diffusion in polycrystalline naphthalene

Studies of self-diffusion in polycrystalline specimens of naphthalene have been carried out using a radioactive tracer technique. The results are consistent with the diffusion proceeding along sub-boundaries in the specimens. Diffusion coefficients for self-diffusion along these boundaries, D g, are considerably higher than those for lattice self-diffusion and vary with temperature according to an expression D g=9.3 ×107 exp (−20.8±1.8 kcal mole−1/RT) cm2sec−2. The results are compared with those for selfdiffusion in single crystals with particular reference to diffusion enhancement by diffusion along dislocations and sub-boundaries in the cryatals.