Codiffusion of $P32$ and $Co57$ in glass-forming $Pd43Cu27Ni10P20$ alloy and its relation to viscosity

In general, the Stokes-Einstein (SE) equation is well accepted for melts. In the supercooled melt a decoupling of diffusivity and viscosity around the critical temperature $Tc$ of the mode coupling theory is observed. The authors measured simultaneously the $P32$ and $Co57$ diffusion in the supercooled melt of the $Pd43Cu27Ni10P20$ alloy from 573 up to $640K$ using the radiotracer technique. They found that P and Co have similar diffusivities and compared them to viscosity data using SE equation. This shows that the time scales of Co and P diffusions are decoupled by up to two orders of magnitude from time scales of viscous flow in the supercooled state.