Grain boundary diffusion through thin evaporated films and ion-plated films (500nm thick) was studied at 150 to 250C. Two methods were independently used to determine the diffusion parameters. These were the so-called first-appearance method and the simplified accumulation method. The values of the activation energies and diffusivities were determined from Arrhenius plots:

evaporated:     Ag-4Sn, D (cm3/s) = 5.0 x 10-7 exp[-0.74(eV)/kT]

evaporated:     Ag-8Sn, D (cm3/s) = 2.0 x 10-8 exp[-0.65(eV)/kT]

ion-plated:     Ag-9Sn, D (cm3/s) = 2.2 x 10-7 exp[-0.53(eV)/kT]

ion-plated:     Ag-12Sn, D (cm3/s) = 1.3 x 10-7 exp[-0.53(eV)/kT]

evaporated:     Ag-14Sn, D (cm3/s) = 2.0 x 10-9 exp[-0.63(eV)/kT]

evaporated:     Ag-23Sn, D (cm3/s) = 1.7 x 10-9 exp[-0.59(eV)/kT]

evaporated:     Ag-41Sn, D (cm3/s) = 3.4 x 10-9 exp[-0.50(eV)/kT]

evaporated:     Ag-59Sn, D (cm3/s) = 7.4 x 10-9 exp[-0.45(eV)/kT] The change in activation energy and diffusivity with Sn concentration was tentatively attributed to changes, in the thermodynamic properties of the samples, which occurred during grain boundary diffusion.

A.Bukaluk: Surface Science, 1989, 213, 464-80