Inter-diffusion and its correlation with dynamical cross correlation in liquid Ce₈₀Ni₂₀

Abstract

We reported the inter-diffusion coefficients in liquid Ce$_{80}$Ni$_{20}$ measured by the sliding cell technique. Combined with the self-diffusion data of Ni measured by quasi-elastic neutron scattering in the literature, it was found that the relationship between inter-diffusion and self-diffusion in liquid Ce$_{80}$Ni$_{20}$ was strongly deviated from the standard Darken equation with an abnormally small dynamical cross correlation factor S (the so called Manning factor) in a range of 0.6–0.8, less than unity in standard systems. Through the calculated distinct diffusion coefficient and its deviation from the standard one, it was discovered that the small S value was directly originated from enhanced distinct diffusion between Ce and Ni atoms and reduced distinct diffusion between Ni and Ni atoms. Because the inter-atomic interaction was not considered in the standard liquids, the present small S factor and intrinsic distinct diffusion coefficients were believed to be resulted from the chemical interaction between Ce and Ni in the liquid. The results provide new evidence of the dynamic cross correlation in liquid diffusion, and thus shed light on the understanding of the correlation between dynamics and structure in liquid alloys.