The ionic diffusion of Cu+ in the β-phase material was studied by using a non-destructive radioactive tracer method which involved the coincidence counting of annihilation γ-ray emissions from the positron decay of 64Cu. Overall, the data (table 259) could be described by:

D (cm2/s) = 42.4 exp[-0.91(eV)/kT]

The results revealed a sharp discontinuity in the diffusion coefficient and the activation energy at the phase boundaries. This behavior contradicted molecular dynamics results, in which the γ-phase was predicted to change continuously into the β-phase. The calculated conductivity values revealed a large disagreement with electrochemical results, and the electrochemical estimates of the diffusion coefficient were much lower than the tracer diffusion results.

J.X.M.Z.Johansson, K.Sköld, J.E.Jørgensen: Solid State Ionics, 1992, 50[3-4], 247-52

Table 259

Tracer Diffusion Data for Cu in β-Phase CuI