Mixing and diffusion of 13C marker atoms in a12C graphite matrix was studied as a function of temperature 10 to 1500K under the influence of bombardment with 70 to 150keV 12C+ and 13 to 20keV D+ ions. At temperatures between 10 and 220K the mixing of the marker atoms was weak, but probably still stronger than pure ballistic mixing. Around room temperature the evaluated diffusion coefficient increased steeply towards a plateau value which was constant up to 1100K. Above 1100K the diffusion coefficient increased monotonically with temperature. This temperature dependence could be understood within a model taking into account mobile defects like interstitials and vacancies and their mutual recombination.

Ion Induced Self Diffusion of Carbon. Roth, J., Möller, W., Poker, D.B., Wittmaack, K.: Nuclear Instruments and Methods in Physics Research B, 1986, 13[1-3], 409-15