中国物理B ›› 2017, Vol. 26 ›› Issue (1): 16102-016102.doi: 10.1088/1674-1056/26/1/016102

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

Abnormal breakdown of Stokes-Einstein relation in liquid aluminium

Chen-Hui Li (李晨辉), Xiu-Jun Han(韩秀君), Ying-Wei Luan(栾英伟), Jian-Guo Li(李建国)   

  1. Laboratory of Advanced Materials Solidification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
  • 收稿日期:2016-02-24 修回日期:2016-10-07 出版日期:2017-01-05 发布日期:2017-01-05
  • 通讯作者: Xiu-Jun Han E-mail:xjhan@sjtu.edu.cn
  • 基金资助:
    Project supported by the National Basic Research Program of China (Grant No. 2011CB012900), the National Natural Science Foundation of China (Grant No. 51171115), the Natural Science Foundation of Shanghai City, China (Grant No. 10ZR1415700), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100073120008), and the Program for New Century Excellent Talents in Universities of China. This work is partially supported by Alexander von Humboldt Foundation.

Abnormal breakdown of Stokes-Einstein relation in liquid aluminium

Chen-Hui Li (李晨辉), Xiu-Jun Han(韩秀君), Ying-Wei Luan(栾英伟), Jian-Guo Li(李建国)   

  1. Laboratory of Advanced Materials Solidification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
  • Received:2016-02-24 Revised:2016-10-07 Online:2017-01-05 Published:2017-01-05
  • Contact: Xiu-Jun Han E-mail:xjhan@sjtu.edu.cn
  • Supported by:
    Project supported by the National Basic Research Program of China (Grant No. 2011CB012900), the National Natural Science Foundation of China (Grant No. 51171115), the Natural Science Foundation of Shanghai City, China (Grant No. 10ZR1415700), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100073120008), and the Program for New Century Excellent Talents in Universities of China. This work is partially supported by Alexander von Humboldt Foundation.

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摘要： We present the results of systematic molecular dynamics simulations of pure aluminium melt with a well-accepted embedded atom potential. The structure and dynamics were calculated over a wide temperature range, and the calculated results (including the pair correlation function, self-diffusion coefficient, and viscosity) agree well with the available experimental observations. The calculated data were used to examine the Stokes-Einstein relation (SER). The results indicate that the SER begins to break down at a temperature Tx (~1090 K) which is well above the equilibrium melting point (912.5 K). This high-temperature breakdown is confirmed by the evolution of dynamics heterogeneity, which is characterised by the non-Gaussian parameter α2(t). The maximum value of α2(t), α2,max, increases at an accelerating rate as the temperature falls below Tx. The development of α2,max was found to be related to the liquid structure change evidenced by local five-fold symmetry. Accordingly, we suggest that this high-temperature breakdown of SER has a structural origin. The results of this study are expected to make researchers reconsider the applicability of SER and promote greater understanding of the relationship between dynamics and structure.

关键词: diffusion, viscosity, dynamics heterogeneity, local five-fold symmetry

Abstract: We present the results of systematic molecular dynamics simulations of pure aluminium melt with a well-accepted embedded atom potential. The structure and dynamics were calculated over a wide temperature range, and the calculated results (including the pair correlation function, self-diffusion coefficient, and viscosity) agree well with the available experimental observations. The calculated data were used to examine the Stokes-Einstein relation (SER). The results indicate that the SER begins to break down at a temperature Tx (~1090 K) which is well above the equilibrium melting point (912.5 K). This high-temperature breakdown is confirmed by the evolution of dynamics heterogeneity, which is characterised by the non-Gaussian parameter α2(t). The maximum value of α2(t), α2,max, increases at an accelerating rate as the temperature falls below Tx. The development of α2,max was found to be related to the liquid structure change evidenced by local five-fold symmetry. Accordingly, we suggest that this high-temperature breakdown of SER has a structural origin. The results of this study are expected to make researchers reconsider the applicability of SER and promote greater understanding of the relationship between dynamics and structure.

Key words: diffusion, viscosity, dynamics heterogeneity, local five-fold symmetry

中图分类号:  (Theory and modeling of viscosity and rheological properties, including computer simulation)

  • 66.20.Cy
66.10.cg (Mass diffusion, including self-diffusion, mutual diffusion, tracer diffusion, etc.) 02.70.Ns (Molecular dynamics and particle methods) 61.20.Ja (Computer simulation of liquid structure)