Evidence of defect-mediated zirconium self-diffusion in amorphous Co92Zr8

We have measured the pressure dependence of Zr-95 self-diffusion in structurally relaxed Co92Zr8 glass at 698 K. The resulting activation volume of (0.9 +/- 0.1)Omega, where Omega is the mean atomic volume, is similar to vacancy diffusion in crystalline solids. This suggests that, while Co does not diffuse via thermal defects in Go-rich Co-Zr glasses [P. Klugkist et at, Phys. Rev. Lett. 80, 3288 (1998)], Zr selfdiffusion is mediated by vacancylike defects. We thus provide evidence of the existence of an opposite Kirkendall effect in interdiffusion between certain amorphous alloys as proposed by K. N. Tu and T. C .