Tracer Impurity Diffusion in Liquid Metals: Period 5 Elements in Gallium

The diflusivities of Ag and of Sn in liquid Ga have been measured and compared with recent data for Cd and In in Ga. The results can be reasonably well expressed by Arrhenius-type relations D = D exp{-Q/RT}, with D =2.2×10 cm /s, @ = 1.68 kcal/mole for Ag, and D =1.6×10 , Q = 1.49 for Sn. At temperatures above some 380 ° K the diffusion coefficients of Ag, Cd and In in gallium are practically equal, while that of Sn lies about 10% lower. Even at the lowest temperatures the D-values of the different tracers vary by less than 10% from a mean. The low temperature points appear to fall somewhat below the best straight lines in the D vs T diagram. No obvious dependence on valency is discerned; the only reasonable systematics implied by the behaviour of the four elements of period 5 is the inverse root dependence on tracer mass.