Entropy-scaling laws for diffusion coefficients in liquid metals under high pressures

QL Cao and JX Shao and PP Wang and FH Wang, JOURNAL OF APPLIED PHYSICS, 117, 135903 (2015).

DOI: 10.1063/1.4916986

Molecular dynamic simulations on the liquid copper and tungsten are used to investigate the empirical entropy-scaling laws D* = Lambda exp(BSex), proposed independently by Rosenfeld and Dzugutov for diffusion coefficient, under high pressure conditions. We show that the scaling laws hold rather well for them under high pressure conditions. Furthermore, both the original diffusion coefficients and the reduced diffusion coefficients exhibit an Arrhenius relationship D-M = D-M(0) exp(E-M/KBT), (M = un; R; D) and the activation energy E-M increases with increasing pressure, the diffusion pre-exponential factors (D-R(0) and D-D(0)) are nearly independent of the pressure and element. The pair correlation entropy, S-2, depends linearly on the reciprocal temperature S-2 = E-S/T, and the activation energy, E-S, increases with increasing pressure. In particular, the ratios of the activation energies (E-un, E-R, and E-D) obtained from diffusion coefficients to the activation energy, E-S, obtained from the entropy keep constants in the whole pressure range. Therefore, the entropy-scaling laws for the diffusion coefficients and the Arrhenius law are linked via the temperature dependence of entropy. (C) 2015 AIP Publishing LLC.

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