The tracer diffusivity of Cu in polycrystalline samples was studied at between 600 and 950C, under an O partial pressure of 1atm, by using serial sectioning or secondary ion mass spectrometry methods. It was found that the present results (table 61) fell upon the same Arrhenius curve, D (cm2/s) = 4 x 100 exp[-256(kJ/mol)/RT]

as did previous data. The diffusivity of Cu was lower than that of Ag, and this was tentatively attributed to an attraction of Ag for O-ion vacancies. It was also suggested that an interaction between cations and O vacancies could explain an increase in the diffusivity of Cu, with decreasing O partial pressure, at 850C.

Site Selectivity and Cation Diffusion in YBa2Cu3O7-δ. J.L.Routbort, S.J.Rothman, N.Chen, J.N.Mundy, J.E.Baker: Physical Review B, 1991, 43[7], 5489-97

Table 59

Grain Boundary Diffusion of 18O in Cr2O3