| Abnormal breakdown of Stokes–Einstein relation in liquid aluminium |
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| 引用本文： | 李晨辉,韩秀君,栾英伟,李建国. Abnormal breakdown of Stokes–Einstein relation in liquid aluminium[J]. 中国物理 B, 2017, 26(1): 16102-016102. DOI: 10.1088/1674-1056/26/1/016102 |
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| 作者姓名： | 李晨辉 韩秀君 栾英伟 李建国 |
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| 作者单位： | Laboratory of Advanced Materials Solidification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China |
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| 基金项目： | 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 T_x(~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 α_2(t). The maximum value of α 2(t), α_(2,max), increases at an accelerating rate as the temperature falls below Tx. The development of α_(2,max) was found to be related to the liquid structure change evidenced by local fivefold 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.
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| 收稿时间： | 2016-02-24 |
Abnormal breakdown of Stokes-Einstein relation in liquid aluminium |
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| Affiliation: | Laboratory of Advanced Materials Solidification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China |
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| 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. |
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| Keywords: | diffusion viscosity dynamics heterogeneity local five-fold symmetry |
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