摘要
The Stokes–Einstein relation D^T/η and its two variants D~τ-1 and D^T/τ follow a fractional form in supercooled liquids, where D is the diffusion constant, T the temperature,η the shear viscosity, and τ the structural relaxation time.The fractional Stokes–Einstein relation is proposed to result from the dynamic heterogeneity of supercooled liquids.In this work, by performing molecular dynamics simulations, we show that the analogous fractional form also exists in sodium chloride(NaCl) solutions above room temperature.D~τ-1 takes a fractional form within 300–800 K;a crossover is observed in both D^T/τ and D^T/η.Both D^T/τ and D^T/η are valid below the crossover temperature Tx,but take a fractional form for T > Tx.Our results indicate that the fractional Stokes–Einstein relation not only exists in supercooled liquids but also exists in NaCl solutions at high enough temperatures far away from the glass transition point.We propose that D^T/η and its two variants should be critically evaluated to test the validity of the Stokes–Einstein relation.
The Stokes–Einstein relation D～T/η and its two variants D～τ-1 and D～T/τ follow a fractional form in supercooled liquids, where D is the diffusion constant, T the temperature, η the shear viscosity, and τ the structural relaxation time.The fractional Stokes–Einstein relation is proposed to result from the dynamic heterogeneity of supercooled liquids.In this work, by performing molecular dynamics simulations, we show that the analogous fractional form also exists in sodium chloride（NaCl） solutions above room temperature.D～τ-1 takes a fractional form within 300–800 K; a crossover is observed in both D～T/τ and D～T/η.Both D～T/τ and D～T/η are valid below the crossover temperature Tx,but take a fractional form for T > Tx.Our results indicate that the fractional Stokes–Einstein relation not only exists in supercooled liquids but also exists in NaCl solutions at high enough temperatures far away from the glass transition point.We propose that D～T/η and its two variants should be critically evaluated to test the validity of the Stokes–Einstein relation.
作者
Gan Ren
Shikai Tian
任淦;田时开(Departments of Physics & Key Laboratory of Photonic and Optical Detection in Civil Aviation,Civil Aviation Flight University of China)
基金
Project supported by the Foundation of Civil Aviation Flight University of China(Grant Nos.J2019-059 and JG2019-19)
