摘要
本文采用分子动力学模拟的方法,对二元混合液体的相分离和玻璃转变过程进行了研究。探讨了二元混合液体在相分离和玻璃转变过程中的动力学和热力学参数的变化、外压对液体相分离和玻璃转变的影响,以及在玻璃转变过程中的动力学不均匀现象。
对于二元Lennard-Jones液体,研究了二元体系中相分离过程、粒子的扩散系数以及相分离域尺寸大小随温度的变化规律。我们发现,相分离域随温度的生长过程可以分为两个阶段,分别是温度比较高的快速生长阶段和低温时的稳定生长阶段;相分离体系中系统的扩散激活能不是常数,而是一个随温度变化的函数。我们还讨论了组元尺寸的变化对相分离过程的影响。结果表明,随两组元中某一组元尺寸σ的减小,系统的扩散性增加,粒子分离程度增强,使系统的相分离域更容易长大,促进系统相分离。
研究了二元混合液体在不同外压作用下的相分离与玻璃转变过程,计算了相分离液体在玻璃转变过程中的结构和动力学特征。我们发现,外压会促进液体相分离的产生,并会提高玻璃转变温度,会使β弛豫出现的温度更高、存在的时间更长,导致系统扩散性降低。我们还首次发现,在这个体系中,液体发生相分离后,两相的玻璃转变温度不同,说明相分离液体的玻璃转变过程存在微观不均匀现象。
Molecular dynamics (MD) simulation is performed to study the phase separation and the glass transition of a binary liquid mixture. Diffusion active energy, self-diffusion coefficient and microcosmic heterogeneity are discussed in the glass transition.
Molecular dynamics (MD) simulation is performed to study the diffusion and phase separation process of binary Lennard-Jones (LJ) liquid. It is found that the growth of phase separation with temperature can be divided into two parts. The first is the fast-growth part at high temperatures and the second is the steady-growth part at low temperatures. Diffusion active energy in the phase separation system isn’t a constant, but a function of temperature and follows the relation of E=a+bTc. The influence of the components size on the phase separation is also discussed. The result shows that the diffusibility increases when the components size decreases. This makes the phase separation more easily.
Molecular dynamics (MD) simulation is performed to study the phase separation and the glass transition of a binary liquid mixture when the external pressure is increased from 0Gpa to 2.75Gpa. The structure and dynamics characteristics in the glass transition process are calculated. We find that external pressure will promote the phase separation, and make the glass transition temperature increase. The external pressure will make temperature become high at which theβrelaxation emerge, the time ofβrelaxation become long, and the diffusibility of the system become low. We first find that the phase separation liquid exist microcosmic heterogeneity in the glass transition.
引文
1 M.Rubinstein and R.H.Colby. Polymer Physics. New York: Oxford University Press, 2003: pl37
2刘向荣,王楠,魏炳波.无容器条件Cu-Pb偏晶的快速生长.物理学报. 2005, 54(04):1671~1678
3王震遐,李学鹏,余礼平,马余刚,何国伟,胡岗,陈一,段晓峰.电子辐照诱发固态相变导致的氮化硼纳米结构生.物理学报. 2002, 51:0620~0624
4廖波,薛郁,陈光旨.N体随机凝聚过程中集团分布的长时渐近行为.物理学报. 2002, 51:0215~0219
5 Li Y S, Chen Z, Lu Y L, Xu G D, Dynamic Scaling Behaviour of late-stage Phase Separation in Ni75AlxV25?x Alloys. Chin.Phys. 2007, 16:0854~0861
6 G.Adam, J.H.Gibbs. On the Temperature Dependence of Cooperative Relaxation Properties in Glass-Forming Liquids. J.Chem.Phys. 1965,43:139~146
7 E.Velasco and S.Toxvaerd. Phase Separation in two-dimensional Binary Fluids:A Molecular Dynamics Study. Phys.Rev.E. 1996, 54:605~610
8 E.Velasco and S.Toxvaerd. Computer Simulation of Phase Separation in a two-dimensional Binary Fluid Mixture. Phys.Rev.Lett. 1993, 71:388~391
9 G.Leptoukh, B.Strickland, and C.Roland. Phase Separation in Two-Dimensional Fluid Mixtures. Phys.Rev.Lett. 1995, 74:3636~3639
10徐锦锋,魏炳波.急冷快速凝固过程中液相流动与组织形成的相关规律.物理学报. 2004, 53(06):1909~1915
11 J.F.Lutsko, D.Wolf, S.R.Phillpot and S.Yip, Molecular-Dynamics Study of lattice-defect-nucleated melting in Metals Using an Embedded-Atom-Method Potential. Phys.Rev.B. 1989, 40(5):2841~2855
12 S.M.Foiles. Calculation of the Surface Segregation of Ni-Cu Alloys With theUse of the Embedded-Atom Method. Phys.Rev.B. 1985, 32(12):7685~7693
13 R.A.Johnson. Relationship between Defect Energies and Embedded-Atom-Method Parameters. Phys.Rev.B. 1988, 37(11):6121~6125
14 K.Y.Chen, H.B.Liu, Q.Z.Hu and Y.C.Li. Molecular Dynamics Simulation of LocalStructure of Aluminium and Copper in Supercooled Liquid and Solid State by Using EAM. J.Phys.Condens.Matter. 1995, 7:2379~2394
15 K.Walter. Computer Simulations of Supercooled Liquids and Glasses. J.Phys.:Condens.Matter. 1999, 11:R85~R115
16 L.N.Hu, X.F.Bian, W.M.Wang, J.Y.Zhang and Y.B.Jia. Liquid Fragility and Characteristicof the Structure Corresponding to the Prepeak of AlNiCe Amorphous Alloys. Acta Materialia. 2004, 52:4773~4781
17 Thomas.J.Lenoky, Scott.R.Bickham, Joel.D.Kress and Lee A.Collins. Density-Functional Calculation of the Hugoniot of Shocked Liquid Deuterium. Phys.Rev.B. 2000, 61(1):1~4
18 Z.J.Tan, X.W.Zou, W.B.Zhang, and Z.Z.Jin. Influences of the Size and Dielectric Properties of Particles on Electrorheological Response. Phys.Rev.E. 1999,59:3177~3181
19陈枫,吴大诚.AB型嵌段聚合物星形胶束的结构,大自然探索,1998, 17(64):41~43
20 J.Wang and W.wang. A Computational Approach to Simplifying the Protein Folding Alphabet. Nature Struct.Biol.1999, 6:1033~1038
21 H.Li, R.Helling and C.Tang. Emergence of Preferred Structures in a Simple Model of Protein Folding. Science. 1996, 237:666~669
22 J.Honeycutt and H.C.Anderson. Molecular-Dynamics Study of Melting and Freezing of Small Lennard-Jones Clusters. J.Phys.Chem.1987, 91:4950~4963
23 C.N.R.Rao, K.J.Rao. Phase Transitions in Solids. McGraw-Hill, New York, 1978
24 G.W.Cahn, Trans.Met.Soc. AIME, 242, 1968, P.166
25 J.E.Hilliard, Phase Transformations. Chapman and Hall, London, ASM, 1970,497~560
26 Sariban A, Binder K. Phase Separation of Polymer Mixtures in the Presenceof Solvent.Macromolecules. 1988, 21:711~726
27 Jo.Won.Ho, Kim.Seung.Hyun. Monte Carlo Simulation of the Phase Separation Dynamics of Polymer Blends in the Presence of Block Copolymers. 1. Effect of the Interaction Energy and Chain Length of the Block Copolymers. Macromolecules. 1996, 29(22):7204~7211
28 Qiliang Yan and Juan J.de Palblo. Critical Behavior of Lattice Polymers Studied byMonte Carlo Simulations. J.Chem.Phys. 2000, 113:5954~5957
29 Gilles Tarjus, Daniel Kivelson and Pascal Viot. The Viscous Slowing Down of Supercooled Liquids as a Temperature-Controlled Super-Arrhenius Activated Process: a Description in Terms of Frustration-Limited Domains. J. Phys. Condensed. Matter. 2000, 12:6497~6508
30 B.Liu, C.H.Tong, Y.L.Yang. The Kinetics and Phase Patterns in a Ternary Mixture Coupled with Chemical Reaction of A + B C. J. Phys.Chem.B. 2001, 105(41):10091~10100
31 S.Y.Zhou, Y.Wang, X.J.Ning. A Quasi-Dynamics Method for Searching for Cluster Isomers. Acta.Phys.Sin. 2008, 57(1):387~391
32 J.Z.Zhao, J.Liu, Y.Zhao, Z.Q.Hu. Molecular Dynamics Simulation of the Pressure Effect on the Formation of Glassy Cu. Acta.Phys.Sin. 2007, 56(1):443~445
33 Z.Y.Hou, R.S.Liu, X.Wang, Z.A.Tian, Q.Y.Zhou, Z.H.Chen. Simulation Study of Effects of Initial Melt Temperature on Microstructure of Liquid Metal NaDuring Solidification Processes. Acta.Phys.Sin. 2007, 56(1):376~383
34 D.Q.Yu, M.Chen. Rigid Multibody Molecular Dynamics Algorithm in Canonical Ensemble. Acta.Phys.Sin. 2006, 55(4):1628~1633
35 Xu Y, Pan Z Y, Wang Y X.低能CU6团簇在CU(001)表面和AU(001)表面沉积的分子动力学模拟研究.物理学报. 2001, 50(1):88~94
36杨玉良,邱枫,唐萍,张红东.高分子体系相分离动力学及图样生成和选择.化学进展. 2006, 18(4):363~381
37 M.P.Allen, D.J.Tildesley. Comput Simulation of Liquids [M]. Oxford: Clarendon Press. 1987, 71~109
38 Walter Kob. Testing mode-coupling Theory for a Supercooled Binary Lennard-Jones Mixture. II. Intermediate Scattering Function and Dynamic Susceptibility. Phys.Rev.E. 1995, 52:4134~4153
39 Zu F Q. Liquid-Liquid Phase Transition in Pb-Sn Metal. Physical Review. 2001, 64B:1~4
40刘燕,耿浩然,孙民华.液态金属粘滞性的研究现状与展望.铸造. 2000, 2:875~878
41 R.Richert, C.A.Angell. Dynamics of Glass-Forming Liquids. V. On the Link between Molecular Dynamics and Configurational Entropy. J.Chem.Phys. 1998,108(21):9016~9026.
42孙春静,耿春霞,刘建同,耿浩然,杨中喜.对回转式粘度仪测量结果影响因素的研究.物理测试. 2004, 1:16~19
43 R.Richert, C.A.Angell. Dynamics of Glass-Forming Liquids. V. On the Link between Molecular Dynamics and Configurational Entropy. J.Chem.Phys. 1998, 108(21):9016~9026
44 D.N.Perera. Compilation of the Fragility Parameters for Several Glass-Forming Metallic Alloys. J.Phys.Condens.Matter. 1999, 11:3807~3812
45 C.A.Angell. Spectroscopy Simulation and Scattering, and the Medium Range order Problem in Glass. J Non-Cryst Solids. 1985, 73(1-3):1~17
46 C.A.Angell, K.L.Ngai, G.B.Mekenna, et al. Relaxation in Glassforming Liquids and Amorphous Solids. J Appl Phys. 2000, 88(6):3113~3517
47 A.P.Sokolov, E.Rossler, A.Kisliuk and D.Quitmann. Dynamics of strong and Fragile Glass Formers: Differences and Correlation with Low-Temperature Properties. Phys.Rev.Lett. 1993, 71:2062~2065
48 S.N.Yannopoulos and G.N.Papatheodorou. Critical Experimental Facts Pertaining to Models and Associated Universalities for Low-Frequency Raman Scattering in Inorganic GlassFormers. Phys.Rev.B. 2000, 62:3728~3734
49 Randall W.Hall and Peter G.Wolynes. The Aperiodic Crystal Picture and Free Energy Barriers in Glasses. J.Chem.Phys. 1987, 86:2943~2948
50 D.C.Dyre, N.B.Olsen. Condensed Matter> Soft Condensed Matter Title: Landscape Equivalent of the Shoving Model. cond-mat/0211042
51 K.Ngai. Dynamic and Thermodynamic Properties of Glass-Forming Substances. J.Non-Cryst.Solids. 2000, 275:7~51
52 R.Bohmer and C.A.Angell. Correlations of the Nonexponentiality and State Dependence of Mechanical Relaxations with Bond Connectivity in Ge-As-Se Supercooled Liquids. Phys.Rev.B. 1992, 45:10091~10094
53 Greer A L. Too Hot to Melt. Nature. 2000, 404(6774):134~135
54 J.Liu, S.Y.Wang, C.P.Zheng, L.J.Xin, D.Wang, M.H.Sun. Glass Transition Temperature of Water: from Simulations of Diffusion and Excess Entropy. Chin.Phys.Lett. 2007, 24(7):2025~2027
55 T.Scopigno, G.Ruocco, F.Sette and G.Monaco. Is the Fragility of a LiquidEmbedded in the Properties of Its Glass? Science. 2003, 302:849~852
56 G.Ruocco, F.Sciortino, F.Zamponi, C.De Michele, T.Scopigno. Landscapes and fragilities. J.Chem.Phys. 2004, 120:10666~10680
57 V.N.Novikov, Y.Ding, and A.P.Sokolov. Correlation of Fragility of Supercooled Liquids with Elastic Properties of Glasses. Phys.Rev.E. 2005, 71:061501~061512
58 S.N.Yannopoulos and G.P.Johari. Glass Behaviour: Poisson's ratio and Liquid'sFragility. Nature. 2006, 442:E7~E8
59 V.N.Novikov and A.P.Sokolov. Correlation of Fragility and Poisson's ratio: Difference between Metallic and Nonmetallic Glass Formers. Phys.Rev.B. 2006,74:064203-064209
60 P.S.Salmon, A.C.Barnes, R.A.Martin and G.J.Cuello. Glass Fragility and Atomic Ordering on the Intermediate and Extended Range. Phys.Rev.Lett. 2006, 96:235502~235505
61 B.J.Alde, T.E.Wainwright. Studies in Molecular Dynamics I: General Method [J]J.Chem.Phys. 1959, 31(2): 459~466.
62 Loup.Verlet, Computer "Experiments" on Classical Fluids. I. ThermodynamicalProperties of Lennard-Jones Molecules. Physical Review. 1967, 159:98~103
63 D.Beeman, Some Multistep Methods for Use in Molecular Dynamics Calculations J.Comput.Chem. 1976, 20:130~139
64 S.Nose. A Molecular Dynamics Method for Simulations in the Canonical Ensemble. Mol.Phys. 1984, 52:255~268
65 S.Nose and M.L.Klein. Constant Pressure Molecular Dynamics for Molecular Systems. Molecular Physics. 1983, 50:1055~1076
66 William.G.Hoover. Canonical Dynamics: Equilibrium Phase-Space Distributions.Phys.Rev.A. 1985, 31:1695~1697
67 S.Nose and F.Yonezawa. Isothermal–Isobaric Computer Simulations of Meltingand Crystallization of a Lennard-Jones System. J.Chem.Phys. 1986, 84:1803~1814
68 K.H.Hoffmann and M.Schreiber. Computational Physics [M], Berlin Heidelberg: Springer-Verlag. 1986, 268~326
69 W.G Hoover. Canonical Dynamics: Equilibrium Phase-Space Distributions. Phys.Rev.A. 1985, 31:1695~1697.
70 H.J.C.Berendsen, J.P.M.Postma and W.F.van Gunsteren, A.DiNoda, and J.R.Haak. Molecular Dynamics with Coupling to an External Bath [J]. J. Chem.Phys. 1984, 81:3684~3690
71 S.Nose. A Unified Formulation of the Constant Temperature Molecular Dynamics Methods. J.Chem.Phys. 1984, 81:511~519.
72 M.Parrinello and A.Rahman. Polymorphic Transitions in Single Crystals:A new Molecular Dynamics Method. J. App.Phys. 1981, 52(12):7182~7190
73 Yan.li.Tang, Yu.Qiang.Ma Phase Separation in two-dimensional Binary Fluid Mixtures: Spontaneous Pinning Effect. Phys.Rev.E. 2002, 65:061501~061505
74 S.Toxvaerd. Molecular Dynamics Simulations of Spinodal Decomposition in Films of Binary Mixtures. Phys.Rev.Lett. 1999, 83:5318~5321
75 M.Grant and K.R.Elder. Spinodal Decomposition in Fluids. Phys.Rev.Lett. 1999, 82:14-16
76 Walter.Kob. Testing Mode-Coupling Theory for a Supercooled Binary Lennard-Jones Mixture I: The Van Hove Correlation Function. Phys.Rev.E. 1995, 51:4626~4641
77程伟东,孙民华,李佳云,王爱屏,孙永丽,刘芳,刘雄军. Cu60Zr30Ti10非晶合金弛豫和晶化过程的小角X射线散射研究.物理学报. 2006, 55(12): 6673~6676
78 H.R.Geng, C.J.Sun, Z.X.Yang, R.Wang, and L.L.Ji. Molecular Dynamics Simulation of the Correlation between the Viscosity and Structure of Liquid Metal. Acta Phys. Sin. 2006, 55:1320~1324
79孟繁玲,李永华,徐耀,王煜明.小角x射线散射确定TiNi薄膜中晶化粒子的长大激活能.物理学报. 2002, 51(9):2086~2089
80 F.Qiu,H.D.Zhang, Y.l.Yang. Oscillatory shear induced anisotropic domain growth and related rheological properties of binary mixtures. J.Chem.Phys. 1998, 109:l575~1583
81 M.D.Ediger, C.A.Angell, S.R.Nagel. Supercooled Liquids and Glasses. J.Phys.Chem. 1996, 100:13200~13212
82 H.J.Jin, X.J.GU, P.Wen, L.B.Wang and K.Lu. Pressure Effect on the Structural Relaxation and Glass Transition in Metallic Glasses. Acta.Mater. 2003, 51:6219~6231
83 K.Samwer, R.Busch and W.L.Johnson. Change of Compressiblity at the GlassTransitionand Prigogine-Defay Ratio in ZrTiCuNiBe Alloys. Phys.Rev.Lett. 1999, 82:580~583
84王海燕,刘日平,马明臻,高明,姚玉书,王文魁.FeSi2合金在高压下的凝固.物理学报. 2004, 53(07):2378~2383
85 H.Li, G.H.Wang, X.F.Bian, Zhang L. Structures of Liquid Aluminium under High Pressure.Chin.Phys.Lett. 2001, 18(4):495~497
86 H.Li, X.F.Bian, G.H.Wang. Molecular Dynamics Study of the Local Order and Defects in Quenched States. Phys.Rev.B. 2003, 67:094202~094208
87 Y.N.Zhang, L.Wang, W.M.Wang, X.F.Liu, X.L.Tian, P.Zhang. Pressure Effect on the Structural Transition of Liquid Au. Phys.Lett.A. 2004, 320:452~458
88李美丽,张迪,孙宏宁,付兴烨,姚秀伟,李丛,段永平,闫元,牟洪臣,孙民华.二元Lennard-Jones液体的相分离过程及其扩散性质的分子动力学研究.物理学报. 2008, 57(11):7157~7163