The impurity diffusion coefficients of Ga and In in -phase material were determined, at temperatures of between 1173 and 1823K, by using diffusion couples and by extrapolating the concentration dependence of the interdiffusion coefficient to infinite dilution. Within the present temperature range, the diffusion coefficients decreased in the order: Ti - Ga - In. Arrhenius plots of the impurity diffusivity (tables 142 and 143) exhibited an upward curvature which was similar to that observed for self-diffusion. The curvature was attributed to the effect of phonon-assisted diffusion jumps via monovacancies with a temperature-dependent migration energy. It was found that the activation energies for impurity diffusion and self-diffusion in the present host were proportional to the square of the radius of the diffusing atom. It was concluded that the size effect predominated during impurity diffusion.

S.Y.Lee, Y.Iijima, K.Hirano: Physica Status Solidi A, 1993, 136[2], 311-21

Table 142

Impurity Diffusion Coefficients for Ga in -Ti

Table 143

Impurity Diffusion Coefficients for In in -Ti