Observation of distinct atomic caging in Ce₈₀Ni₂₀ metallic melts

We have studied the effect of temperature on atomic caging in Ce₈₀Ni₂₀ alloy liquid using quasi-elastic neutron scattering. The atomic transport mechanism in this liquid is found to be via a jump diffusion process. This is evident from the momentum transfer (Q) dependence of the mean relaxation time. The diffusion coefficients of Ni in Ce₈₀Ni₂₀ melts exhibit Arrhenius temperature dependence while, close to the melting temperature, the residence time of Ni atoms increases exponentially with decreasing temperature. On the other hand, other binary metallic liquids having the Arrhenius temperature dependence of diffusion coefficient exhibit a linear variation of the residence time with temperature. We believe that the exponential increase of the residence time on decreasing the temperature in Ce₈₀Ni₂₀ liquid is due to the large size ratio of Ce/Ni and glass-forming ability of the alloy melt.