Codiffusion of ~(32)P and ~(57)Co in glass-forming Pd_(43)Cu_(27)Ni_(10)P_(20) alloy and its relation to viscosity

摘要

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 T_c of the mode coupling theory is observed. The authors measured simultaneously the ~(32)P and ~(57)Co diffusion in the supercooled melt of the Pd_(43)Cu_(27)Ni_(10)P_(20) alloy from 573 up to 640 K using the radiotracer technique. They found that P and Co have similar diffusivitis 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.