Electromigration of gold (high concentration) in lead

The steady state method was used to study the electromigration of ¹⁹⁵Au in lead doped with 680 ppm Au. In the temperature range 165–270°C Au migrates toward the anode, as in the case of more dilute solutions; but the effective charge increases in magnitude with decreasing temperature at a faster rate than that observed for dilute Pb(Au) samples, so that the difference between the effective charge for the 680 ppm samples and that for dilute samples becomes larger as the solubility limit is approached. A simple model, which allows for formation of Au doublets in equilibrium with the singlets, predicts an apparent increase of Z¹ with concentration of impurity at lower temperatures somewhat greater than the observed effect.