The diffusive behavior of 198Au in single crystals was studied at 300 to 500C. The results for c-axis diffusion depended upon the diffusion source, and involved both fast and slow processes:

solid, slow:     D (cm2/s) = 2.5 x 10-5 exp[-23.2(kcal/mol)/RT]

solid, fast:     D (cm2/s) = 2.0 x 10-3 exp[-16.6(kcal/mol)/RT]

gas, slow:     D (cm2/s) = 7.0 x 10-2 exp[-31.6(kcal/mol)/RT]

gas, fast:     D (cm2/s) = 1.5 x 10-3 exp[-15.3(kcal/mol)/RT]

J.Zmija, M.Demianiuk: Acta Physica Polonica A, 1971, 39[5], 539-53